added deleted object management
coder standards
used new constant
Merge branch '7.x' of github.com:Islandora/islandora_solution_pack_book into 7.x
added form alter
added additional mimetypes
take care of this outstanding issue via @nigelgbanks comment from https://groups.google.com/forum/#20bookobjects/islandora/8Ptf6ZVHkA4/JlS16B6SMMsJ
Merge pull request #98 from ruebot/7.x

take care of this outstanding issue via @nigelgbanks comment from https:...
added ability to ingest jpeg pages
Merge branch '7.x' of github.com:Islandora/islandora_solution_pack_book into 7.x
made derivatives state aware
added form alter to allow jpegs
Make comparison of extensions in zip addition case insensitive.
Make logic more concise.
Use format_plural(), 'cause it's awesome.
Get rid of explicit batch_process() call, and avoid dividing by zero...

... Don't run the batch if there are no files to add in the ZIP file.
Coding standards... squash some whitespace.
moved derivative logic to paged content module
added two function to manage property updates
fixed typo