Don't repeat documents.

Prevents a document to be delivered to a user who already scraped it.
Validity Rate for documents

First and not very elegant implementation of the "validity rate" funcion
for individual fields of a documents or avarage for all of the fields.
More validity logic

Added validated & some fixes.

Also: moved pending documents logic from view to
DocumentSet: get_pending_documents
Fix redirect

Removed redirect from form_detail that prevented success in client side
$.post.

Also: moved pending documents logic to model.
Optimize getting pending documents query

Also, fix bug when saving entry without user.
Bug fixes
fixed annoying typo
added document name to template

Just for testing purposes.
get_pending_documents with threshold per field.
Rollback fix redirect to add it to another branch
Fixed answer ok redirect.
Merge pull request #4 from gusajz/fix_redirect

Fix redirect