Convert Minify_Source::lastModified to ->getModifiedTime() #114
last_modified is always integer, no need to check for null
tests: use Minify_Source
Removes support for arbitrary objects for sources
Merge branch 'glensc-lastmodified' into 3.0
cherry-pick 30ba097ee0cf92978e12c7f7c6bd7c7381f7e35a

First working copy, manages .less files correctly
Conflicts:

	min/lib/Minify.php
	min/lib/Minify/Controller/MinApp.php
use autoloader
drop LessCss_Source, not needed
composer: optional less support via lessphp