Create general search for all documents

[smcalilly]

The current searching works where each document type is a separate search. Sometimes users don't know the document type they're searching, and they need a general search that searches all of the documents.

This will be a bit tricky with django-haystack, since the search indexing is dependent on a single model. Each model has a separate search index. We need to figure out if django-haystack supports multiple models for a single index, or come up with a good way to index all of the different models in one index.

[smcalilly]

django-haystack doesn't provide a way to do this. We're gonna achieve this in the view by chaining a query with all the indexes