This is node-style callbacks for #676. This allows us to release
the new callback style without introducing backwards incompatible
changes (or making changes to the binary from 2.0.1). If a node style
callback is provided, it will be used. For now, this stacks with
the original `options.success` and `options.error`, although it can
be trivially changed to an xor.

To highlight the new interface, a separate `describe` was added to the
tests which identifies the `{options}, cb` interface and tests it
independently.

Build: Uses v8 version instead of runtime name.

The new binary path format is:
`<platform>-<arch>-<v8 version>/binding.node`

Issue URL: #694.
PR URL: #695.

Render options in callbacks as this.options

This patch and tests introduces a context for all callbacks currently
in node-sass. Right now, they run w/ an ambiguous context, making the
`this` keyword not helpful to importer developers (and eventually
custom function developers). This creates a context object, adds the
render options to said context object, and then uses that context for
importer, success, and error callbacks via `this.options`.

By using a context instead of just `.call(options...)` there is a hook
for later should we find additional environmental information is
valuable to importer / custom function developers such as the node
environment, node-sass version, etc.

Misc. Fixes

On Windows, process.execPath does not
get resolved symlink path. This commit
fixes the issue.

Related Issue: iojs/io.js#851.
PR URL: #668.

* Returns json-string error from LibSass as is.
* Extends empty error object with parsed JSON.

Note: The reason why  NanError  is not used
because LibSass returns error as JSON string
with  message  as member, so we would have to
reparse and reassign the obj in that case.

Issue URL: #675.
PR URL: #668.

* Reason: njs v0.11 is not relavent any more.
* Solution: Update to node v0.12 with which
            node-sass v2.0.1 is compatible OOTB.

Code: Minor fixes.

Package: Updates libsass verion

* Locking down v2.0.0.
Related Issue: #602.

Improve install script

Misc. Fixes

* Promotes node.js to v1.2.

Code: Minor refactoring.

Include correct header for malloc related functions.

Build: Produces identifiable binary name

The new format is:
{platform}-{arch}-{runtime}-{major.minor}
where major and minor version belong to
the runtime.

Related Issue: #655.
PR URL: sass/node-sass#657.

Package: Adds pangyp to devDependencies

* Updates packages to latest versions.

Don't exit if an error occurs while watching

If the user specified to watch a directory/file and an error occurs we shouldn't stop the process.

Add docs badge to README

specifying outputStyle default value