Admin page for the audio solution pack

- discussed here: https://groups.google.com/forum/?fromgroups=#!topic/islandora-dev/p-dyXq7M9cc
- allows a path to the LAME executable to be set
- allows select of a LAME preset
address issues outlined here: https://github.com/Islandora/islandora_solution_pack_audio/pull/36#issuecomment-15134805
Merge pull request #36 from ruebot/feature/admin-page

Feature/admin page