Fragment handling in data-uri function 1959

The change removes #fragment from filePath before readig the file and adds
it back to the end of the generated uri.
Fix missing ^, causing parse error. Fixes #2154
Pass options object to parser.parse in less.render.
Added case insensitive units handling. Issue #2096
Merge https://github.com/less/less.js into case-insensite-units-2096

Conflicts:
	test/css/comments.css
	test/less/comments.less
Merge pull request #2181 from SomMeri/case-insensite-units-2096

Case insensitive units parsing and comparison