Updates file display for JP2.

Adds support for displaying files in Exhibit Builder for Omeka 1.5.

Removes static array of sizes from the Jp2_Renderer class.

Relies on methods available in Djatoka OpenURL Services to construct URL to
image asset. Should now be able to pass any valid parameters to the display
method to return a variety of image options.

See http://sourceforge.net/apps/mediawiki/djatoka/index.php?title=Djatoka_OpenURL_Services
for possible options.
Merge branch 'feature/jp2-derivatives' into develop