Support for modern webdev practices/technologies:

- Ability to group files of like type before processing.  Useful for having django_compressor work for things like separate mixins.less and page.less files
- Ability to redirect teh output of teh template tag to a template context variable.  Useful for using the compressed Url with asynchronous resource loaders (e.g. yepnope.js, require.js, etc.)
- Ability to specify options in the template tag that are passed through to the compressors, precompilers, and filters.  Currently supported options:
	group_first - if 'group_first=true' is specified, files of like type will be concatenated before being handed to precompilers/filters
	deferred - if 'deferred=true' is specified AND 'as <name>' is specified the results of the template tag are stored in a <name> template context variable
- Naming a tag by using 'as <name>' like other pythonic and django-y things
- Can specify all tag arguments after the type  (css|js) in any order
Merge commit 'cd64b116f0252835a5bafb3984f8f1afb580bafc' into develop