Let users select band to keep
Ask user what bands they would like to keep.

Might be a good idea to write in a default command-line
argument to let people just grab the first band --
that is usually the one that people will be most interested
in anyways.
Fixed as per Bennet's suggestions

- Added exception handling on bad input
- Used set to check for inclusion
- Won't reprint options on bad input
Merge pull request #1 from ahinz/band-selection

Band selection