Custom view controller for selecting gallery images

Presents albums and images in a similar way to the built-in iPad Photos app. Allows for multiple selection, but presently is hooked up only for single image selection. Takes much better advantage of screen real estate on iPads.
Merge pull request #91 from montehurd/multiGallerySelect

Custom view controller for selecting gallery images
Localisation updates from http://translatewiki.net.
Localisation updates from http://translatewiki.net.
Details page makeover. Image pinchable in-place. Slide-able details table.
Cleaned up some private vars to adhere to "varname_" convention.
Ensured keyboard hidden when details view goes away.
Whitespace cleanup
iPad tweaks. Larger image. Details panel appears higher on screen.
Added back buttons to category and licensing pages.
Centered upload and open wiki page buttons.
Updated details page navigation bar prompt.
Expanded the details page image's initial size just a small amount.

Looks much better on iPad now as there's now just a bit of overlap which causes the image to extend beyond the nav bar buttons.
Initially expanded the details page image for non-iPads too.
Tapping disabled upload button on details slides details up.
Made image overlay not go completely dark when details slides up.
Made "Describe and Upload" msg appear *after* details scrolls down.
Made details slide perfectly beneath nav bar when auto scrolled.
Made details overlay look more like design mockup.
Whitespace cleanup.