feat(Functions): implements `escape-css` function
chore: bumps the version
refactor(sass): `arkush` -> `arkush/extensions`
chore: bumps the version
Merge branch 'release/v0.9.2'

Conflicts:
	arkush-extensions.gemspec
	lib/arkush/extensions/functions.rb
	lib/arkush/extensions/version.rb
fix(gemspec): adds Ruby Racer as a development dependency
Merge branch 'hotfix/execjs-development-dependency'
Merge tag 'execjs-development-dependency' into develop

v0.9.2