Override routes to record view to be /view/:id.

Also overriding librarian_view but keeping all other resources at /catalog.
adds support for when a search term is not given
Merge pull request #303 from sul-dlss/routes

[PROPOSAL] Change routes to be /view
Merge pull request #305 from sul-dlss/callnumber-fix

Adds support for when a search term is not given
adds preview type parameter to helper
adds gallery preview plugin