Removed "voucher" from text.  Apparently "voucher" is something very specific.  We don't actually require anything specific when we ask the user if they have a specimen available for research.  So just avoiding the issue altogether and making it a nice generic "specimen" instead.  Also fleshed out what "collection number" means in create_observation form help text.
Removed "voucher" from text.  Apparently "voucher" is something very specific.  We don't actually require anything specific when we ask the user if they have a specimen available for research.  So just avoiding the issue altogether and making it a nice generic "specimen" instead.  Also fleshed out what "collection number" means in create_observation form help text.

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