Updated Models: Composer, Movement, Corpus
Added: Indexer/Deleter in Django admin

Signal handlers in models added
Schema.xml updated with general fields, and fields specific to above models
Indexer and deleters in Django admin ui added
Models Updated: piece; Schema Updated & Reorgnanised; search_results.html updated

model for piece updated with request handlers
schema updated for additional fields
search_results now included in search; added html for query results of type composer, movement, corpus, piece
Attempt to handle null entries in ForeignKey fields

added
if statements to stop trying to find null subclasses
Models updated with request handlers, Schema also updated

With exception of userprofile, todo, tag_hierarchy, query, attachment, download
Also with exception of ManyToManyField fields