Improve species search interface.

[jdeck88]

It would be nice to improve the genus and species search options.
Some options:

1. retain the genus dropdown (for all genera) and then when user selects a genus, provide a dropdown to select associated species names for each genus.

2. Have a single scientific name box that uses autocomplete and user can select any scientific name (this would include options to just select by genus amidst options for genus+species).

3. (current option) retain the genus dropdown and then another box to simply select a scientific name that the user enters. This is easiest (and already implemented) but user must type the species name correctly.