If compiling using the debug build of node
-DDEBUG and -D_DEBUG flags are automatically
added.

This causes libsass to produce additional
debugging output that may interfere with
tests.

Once this is resolved, this can be reverted.

Reported-as: https://github.com/sass/libsass/issues/1518

Fixes: https://github.com/sass/node-sass/issues/1123

Introduce libsass version checking in cli.js
and skip the test if running with libsass 3.2.5
or older.

Update to the new Travis CI infrastructure.

http://docs.travis-ci.com/user/migrating-from-legacy/#Why-migrate-to-container-based-infrastructure%3F

Update reference of 'multi-file' to 'directory'

Standardise on cross-spawn for spawning child processes

The multi-file terminology is unintuitive and could be seen as
suggesting we support multiple input files, when in fact we're
describing directory support.

Empty data string is not a file name

There a known issues with `spawn` on Windows i.e. joyent/node#2318.
As a work around we sometimes use
[cross-spawn](https://www.npmjs.com/package/cross-spawn). We will
move all usage of `spawn` to `cross-spawn`.
Closes #1015.

Revert "Workaround the segfault that occurs when used with fsevents"

This reverts commit 3166b613.

Ensure we have nan@^2.0.8

This is to make sure binaries affected by
https://github.com/sass/node-sass/issues/1107 are never built

Remove C++11 feature in order to be
able to compile against libstdc++.so.6.0.9
on MacOSX.

Allow to link the binding against
oldish libstdc++.6.0.9 installed on MacOSX
(from gcc 4.2.1)

Workaround the segfault that occurs when used with fsevents

fsevents@0.3.8 introduces a segfault that manifests when used with
node-sass. fsevents is widely popular. As a mitigation we've added
fsevents@0.3.7 as an optionalDependency.The intention here is the
prevent users install node-sass@3.3.x and fsevents@0.3.8 by using
npm's deduping behaviour.

Intended to fix https://github.com/sass/node-sass/issues/924

node-gyp is using process.config.target_defaults.default_configuration
to check which configuration is about to be used, but this
can be overriden by particular engine's config.gypi file.

Since we do not support such a cross compilation anyway,
use this variable in place of a hardcoded default.

Instead of introducing another option to force the use
of 'Release' we should read and pass options to node-gyp.
This is not implemented here.

To speed up a build and avoid bombarding
nodejs.org and iojs.org with connections we should
cache what we download via npm and node-gyp.

CI: Adds explicit runtime versions in job matrix

* The artifact will be available under job details in `Artifacts` tab.
* URL format: `https://ci.appveyor.com/project/sass/node-sass/build/<build-id>/job/<job-id>/artifacts`.

Updates appveyor.yml.

Related: #1096

Be explicit about which runtime versions travis should test

Use new libsass GitHub link

In case of exception occuring during construction
of a Sass type instance just return Undefined value,
as the delayed JS exception will pop up later.

The following code:

    var sass = require('./');
        sass.render({
        data: 'div { color: foo(); }',
          functions: {
            'foo()': function() {
              return sass.types.Color(2,3);
            }
          }
    });

now results in an libsass error

     Constructor should be invoked with either 0, 1, 3 or 4 arguments

instead of V8 abort

     FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal