v1.5.1

Added source-map-URL option
Fixed a bug which meant the minimised 1.5.0 browser version was not wrapped, meaning it interfered with require js
Fixed a bug where the browser version assume port was specified
Added the ability to specify variables on the command line
Upgraded clean-css and fixed it from trying to import
correct a bug meaning imports weren't synchronous (syncImport option available for full synchronous behaviour)
better mixin matching behaviour with calling multiple classes e.g. .a.b.c;