support for a new source mapping URL declaration

http://updates.html5rocks.com/2013/06/sourceMappingURL-and-sourceURL-syntax-changed
Merge pull request #4 from dwo/js-parse-error

catch JS_Parse_Errors in uglify processor
Merge pull request #5 from somebody32/master

Fixed sourceMappingURL comment for IE
Bump version to 0.3.5.
catch the other potential JS_Parse_Error too