Update dependencies (including node-sass v3.7.0)

[mandrean]

A number of dependencies can be updated, eslint and node-sass being a few.

[xzyfer]

We use the latest node-sass

[mandrean]

No? node-sass v3.7.0 released a day ago https://github.com/sass/node-sass/releases

[xzyfer]

I am aware as I released it. We're locked to node-sass@^3.4.2 which means you'll get the latest node-sass@3.x release on a new npm install.

I suggest familiarising yourself with SemVer.

[mandrean]

Yes of course I know about semver. Sorry, overlooked the carret operator.

[mandrean]

@xzyfer How about all the other dependencies that can be updated? Especially eslint (v1 -> v2), but also globule (v0.2 -> v1, which in turn updates an old lodash subdependency), should (v7 -> v8) and autoprefixer-core (v5 -> v6).

My PR was going to include them as well.

[xzyfer]

They're dev dependencies so I'm not too fussed. I've bumped the trivial ones in #490.
The postcss ones are trickier because postcss 6 broke node 0.10 support.