Hidepw

This branch does 3 things

1. Ignore the binary `screenxtv-gcc-client`
2. Prevents the echoing of a user's password as they enter it
3. Informs the user when the login credentials they have entered are invalid

Regarding #2, please verify on OS X. The source I used was pretty much directly from the GNU http://www.gnu.org/software/libc/manual/html_node/getpass.html.