Fixed #5825 -- Modified the custom command loader to allow for explicit...

Fixed #5825 -- Modified the custom command loader to allow for explicit specification of the project name, even if the project directory isn't in the python path. This brings custom command loading into alignment with application loading. Thanks to jdetaeye@frepple.com for the original report, and to abozanich for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8227 bcc190cf-cafb-0310-a4f2-bffc1f526a37