parse file to css string
refactoring
Merge pull request #1 from LinusU/patch-1

parse file to css string
stylus: new api
test: basic functionality
readme: new api
older php compatibility
fixed data uri regex (closes #3)

Credit for the fix to @michalhisim
cleanup
only parse import if it's stylus
Merge pull request #6 from LinusU/master

Added tests and new api for parsing single file or string