Upgrade libsass to latest master SHA hash

Tests didn't run on my local machine, however when
checking with the untouched node-sass they didn't
run either with the same errors.
fix travis.yml because libsass now uses a submodule for sass2css
Fix ShellJS resolutions on Windows

https://github.com/arturadib/shelljs/issues/41
Added metalsmith-sass to README.md
Merge pull request #319 from PxlBuzzard/patch-1

Added metalsmith-sass to README.md
Merge pull request #309 from mweibel/update-libsass

Upgrade libsass to latest master SHA hash
Update libsass to support BEM style selectors
Merge pull request #320 from keithamus/fix318

Update libsass to support BEM style selectors
Updated libsass too fix the Windows build
See #318
Merge pull request #323 from LaurentGoderre/fix-windows

Updated libsass too fix the Windows build
Updated libsass to v2.0.0

Relevant to #324
0.9.0
Fixed copy-pasta error
Merge pull request #317 from nschonni/fix-shelljs-on-windows

Fix ShellJS resolutions on Windows
add logo - fixes #327
Update install instructions for Ubuntu build issue

Closes gh-237
Merge pull request #330 from sindresorhus/logo

add logo - fixes #327
Added twitter link to readme
readme - svgify badges
Merge pull request #329 from andrew/ns-ubuntu-install-docs

Update install instructions for Ubuntu build issue