Lucyw/empty version

My colleague noticed that if you gem install from the command line but don't include a version, it is still run with -v (because empty strings in ruby return true), and gem install -v without a version errors out.  All I did was added an "if version.length > 0" to the gem install process (the if...else was already in place), and a test to make sure that it still worked.  Let me know if anything else needs to be modified!  
Trivial notes: say tempfile(s), and remove the exclamation point from the end because it's going to be after a newline anyway.