Fix bug where tabs throw error after specimen search
Fix bug where tabs throw error after specimen search

An error was thrown by clicking a sort-order tab after a pattern search for specimens.
The tabset on the search results page calls `SpecimenController#index_specimen`, but that method didn't exist.

This commit adds the `index_specimen` method.
The commit finishes https://www.pivotaltracker.com/story/show/104646714

raysuelzer/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,raysuelzer/mushroom-observer,JoeCohen/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,raysuelzer/mushroom-observer,raysuelzer/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,pellaea/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,raysuelzer/mushroom-observer,raysuelzer/mushroom-observer,MushroomObserver/mushroom-observer,raysuelzer/mushroom-observer,JoeCohen/mushroom-observer