added dynamic file gene_search.css to gitignore.
added dynamic file gene_search.css to gitignore.

I am considering whether to put a
blanket ignore with the exception of the ones we need instead. For now this
works.

kevinkle/semantic,kevinkle/semantic,superphy/semantic,superphy/semantic,superphy/semantic,superphy/semantic,kevinkle/semantic,kevinkle/semantic