Minor downloads bug fixed

splitext returned .ext, not ext - messed with download checkboxes
User patching of download objects implemented for pieces

Added:
View for adding attachment to download objects added in forms
Url mapped
Template & serializer for pieces updated to interact with view using request
Piece detail attachments update

Now only shows interface for adding attachments to download only if there are attachments
User can now add mvt attachments to downloads

Updated serializer & template for movements to let users to add attachments to their download objects
Download object's attachments can be removed

From /downloads/ interface, user can choose which files to remove
Attachment removal now works with extensions

User can remove all files of ext .____ from their download object
Toggle all implemented in downloads template

Lets user select/deselect all files; jQuery script added
Merge branch 'master' of github.com:ELVIS-project/elvis-site
Fixed: Ignore all media files
Fixed: Database user/passwords for production

Database settings for local & test server machines were different; if statements added to change settings when necessary
Changed: Attachment post parameters

Parameters passed in request for changing downloads' attachment field changed to attachment ids to allow for field modification
Removed: debugging prints

In search.py (add if statements later for debug mode)