Add failing test for imported mixin with wrong path

When relative URLs are on, and there's an image referenced via url(...),
if the URL is unquoted, the generated CSS duplicates the base path
Adding gsub function
Adding gsub function
Adding capture group test case
Merging remote
Fix missing parameter to Quoted - Fixes #1562
Fix bad json - extra ,
Fix duplicate selectors sometimes generated in extends. Fixes #1591. Fixes #1581
support nested selectors in extends. part fixes #1580
make the inline option more obvious. fixes #1603
Fix error message when putting guards on a single selector
do not re-import the re-entry file. Fixes #1484
fix spacing issue with extends and fix tests
1.5.0 release
added gradle based test suite, reviewed rhino integration
added gradle based test suite, reviewed rhino integration
merged upstream/master
normalize quotes to apostrophes in error messages from javascript evaluation (unify node/rhino error message)
fixed some jshint errors
removed Makefile (again), fixed grunt rhino build