Removed 55 since it was part of a prerelease Node 8 only

Improved the grammar and clarity of the instructions in this project's README

* Remove Node 0.10 and 0.12 from travis config

These will always fails now due to https://github.com/sass/node-sass/issues/2100. We manually verify support when building release binaries so there's no value in failing CI. It's scary to contributors.

* Remove Node 0.10 and 0.12 from appveyor config

These will always fails now due to https://github.com/sass/node-sass/issues/2100. We manually verify support when building release binaries so there's no value in failing CI. It's scary to contributors.

* Link to the troubleshoot guide for Node < 4 installation issues

Help people search for keywords because noone reads the help guides anyway.

Fix a couple of typos and minor Markdown tweaks.

Thanks to @drook for reporting it via #2033

Closes #2027

Fixes #1952
Closes #1956

- fixes issues with transitive dependency scss-tokenizer
- allows graph to follow symlinks

This logic is all tightly coupled in the bin. This logic has been
notoriously impossible to test due to weird fs timing issues. By
extracting the actual logic we're now able to test it in isolation.

With this in place replacing Gaze (#636) becomes a viable option.
This PR not only massively increases our test coverage for the
watcher but also address a bunch of known edge cases i.e. orphaned
imports when a files is deleted.

Closes #1896
Fixes #1891

Readme: Fix typo in alt text of Slack Badge

Add Electron ABI versions

This adds the respective Electron ABI versions to `getHumanNodeVersion()`
to enable running `node-sass` under Electron where the ABI versions differ from Node's.

* Move Contributing.md under .github
* Move ISSUE_TEMPLATE.md under .github

* Chore: Move ISSUE_TEMPLATE under .github

Closes #1983

Run the initial listing before running the full matrix of builds

Update module version for Node 8

TODO(xzyfer): fix this post Node 8

Update module version for node v8.x

V8 5.7 landed recently in node core, causing the module version to get bumped.

Add Node 8 to the support versions lists

Use hardcoded process values rather than inspecting the current
environment.

This is a workaround for nodejs/citgm#389. The install/build flow
needs to be updated so that unsupported environments result in an
informative warning instead of a failure.

Closes #1838
[skip ci]