This slows down the release builds and in the worst case scenario
causes a single job failing meaning we need to rerun the entire build.

Problems with tests will have been caught we'll before we start
building release binaries.

Closes #1486

Node 6.x has trouble including modules
from MS-DOS drives created with subst.exe.

Since we use use subst only to set
symbols paths in the PDB file, let's
revert to the C: drive when doing tests.

Workaround for: https://github.com/nodejs/node/issues/6500

Previous we manually installed NVM and did the version switching
ourselves. This was required because Trvais didn't support NVM
on OSX builds. This has since [been fixed][1] so lets see how it
goes.

[1:][https://github.com/travis-ci/travis-ci/issues/2311]

This was previously attempted in #1413. Shortly after it's
release proxy users started experiencing installation issues so
this was reverted. It was later determined that #1458 was likely
at fault for the proxy issues.

Full credit for this patch goes to @delitescere.

I've also taken the liberty of cleaning the request config generation.

Fixes #1333

This was partially addressed by bumping NAN in #1496.

https://github.com/nodejs/node/issues/6216
https://codereview.chromium.org/1839983002/patch/1/10002

Fixes #1484

This removes the deprecation warning in Node 6

The human friendly name for an unknown platform, arch or runtime
is currently `false`. With this patch the user is better informed
as to why their environment is unsupported. The raw value is also
output to ease with bug reports.

Closes #1487

v3.6.0: Bump LibSass to 3.3.6

This reverts commit c2d24c23.

Unfortunately got does not have good [proxy support][1] which
was missed during review.

Fixes #1458

[1]: https://github.com/sindresorhus/got/issues/79

This reverts commit 5e21f475.

The solution implemented was not equivalent and resulted in issues
for users with proxies.

Fixes #1458

Fix script/build.js logic

Also, do not add additional spaces.

v3.5.0

Log the error when there is a problem with the binary

This is a messy first cut. We can revisit this in upcomming patches.
The value this will bring to debugging installation errors makes
this worth considered we're about to release a LibSass bump.

Fixes #1161

Bump LibSass 3.3.5

Fix a regression in binary verification

A regression introduced in 22c560c7 broke binary verification
causing the binary to always be built locally.

Fixes #1434

Ouptut a deprecation warning to stdout when using process.sass

This is an undocumented internal API that will be removed. Access
`process.sass` will produce the following warning.

>Deprecation warning: `process.sass` is an undocumented internal
that will be removed in future versions of Node Sass.

Better error messages for missing binaries

This is another iteration on improving the infamous
>The `libsass` binding was not found

Messages will now provide more useful information which will
- give users a chance to resolve the problem themselves
- give us more debug information from the error message alone

Error messages produce now will look like:

>Node Sass does not yet support your current environment: OS X 64-bit with Node.js 4.x
>For more information on which environments are supported please see:
>http://....

>Node Sass could not find a binding for your current environment: OS X 64-bit with Node.js 4.x
>Found bindings for the following environments:
>  - OS X 64-bit with io.js 3.x
>  - OS X 64-bit with Node.js 5.x
>This usually happens because your environment has changed since running `npm install`.
>Run `npm rebuild node-sass` to build the binding for your current environment.

>Node Sass could not find a binding for your current environment: OS X 64-bit with Node.js 4.x
>This usually happens because your environment has changed since running `npm install`.
>Run `npm rebuild node-sass` to build the binding for your current environment.

Remove use of global process.sass

This replaces the global `process.sass` with proper module exports.
Unfortunately `process.sass`, although undocumented, is available
to other modules. This patch keeps the existing public API available
until we bump the major.