Use standard/flexible file options

Task changes to allow for flexible file options as found in the
grunt-contrib projects.
Taking hints from grunt-contrib-less to allow for compiling single files
separately, dynamic mappings and combining.
Removed extension option as this is determined by flexible file
matching.
Removed MT time ignoring, this can be easily done with the grunt-newer
plugin.
Errors are ignored and skipped by default to match how other grunt
plugins work.
Added examples in the grunt file and test both mechanisms with the same
old unit tests.
React recommends Node 0.10 and travis is also set to 0.10, updated
package file to include that version check.