Fix references mgmt

This pull request finishes stories: https://www.pivotaltracker.com/story/show/49151933 and https://www.pivotaltracker.com/story/show/59216422 , regarding management of References in the Species+ Admin tool:

**Taxon Concept References:**
- Improved form layout;
- User can now edit added references;
- Bugs with javascript that were preventing the search for citations are now fixed;
- User can select excluded taxa for a given reference
- User can see the count and list of excluded taxa from a taxon concept's reference page (check Mammalia for an example)
- User can see from which Taxon Concept is it inheriting each standard reference  (changed the 'standard_references' method to return the taxon_concept_id for which the taxon_concept_reference object was issued)
- User can no longer edit a references' citation from the taxon concept's references form. But now the list of references links to the References' index page with the query set to the citation of that reference. To make it easier for users to edit the citation;

**Distribution References:**
- Fixed bug with javascript that was preventing the search of existing references;
- Improved layout of the form;
- User can no longer edit a reference's citation from the distribution's references form. But now the list of references links to the References' index page with the query set to the citation of that reference. To make it easier for users to edit the citation;