Created the media gallery. First step towards completion of #59.

There will be a lot of stuff to add to hosting in order to make it work. It will be written within the ticket.
Made sure iron-router will not bust for bigger files for media gallery #59.

Related to https://github.com/EventedMind/iron-router/issues/710. Will come back later when we move to next meteor version.
Moved to vendor folder.
Completed the gallery (#59).
Merge branch 'master' into media-gallery
Added media gallery modal to playlists edition.
Get checksum of uploaded file.
Save playlists with media.
Can now upload files directly from playlist edition.
Fixes #66. An admin now chooses a group and only sees related content.

The box to choose a group is within the admin's profile. Should we set it up somewhere else?
Also, do we need an indicator of which group we're in at the moment?
Fixed #67. Using NProgress instead of loading template.
Moved vendor files to /vendor/
Fixes #68. Each color is assigned to a position.
Uploading directly from the playlist edit page.
Fixes #70. When all files are deleted from playlist, playlists files are empty.
Do not show file list header when there are no files.
Fixes #69. Deleting media deletes corresponding files.
Removed the 'effect' button as it has no use for now.
Restore blank sort on rendered.
Restore blank sort on rendered.