Add changes to support latest libsass version
Implements source map options
Exposes `sass_compile_file` function

Needed for automatic indented sass syntax recognition
Exposes `sass2scss` function
Implements precision option
Adds full sass spec test suite
Adds optional options for sass context

Source map URLs are relative to output path
Adds travis-ci configuration
Merge pull request #4 from mgreter/clean-libsass-update
Fixes README.md after the transition to SASS org

Added .gitattributes to fix LF types (for tests)
Adds and fixes unit tests
Changes official libsass with patched libsass
Added more tests for latest libsass patches