retro-contest does not exit with an appropriate status

[ConradBailey]

I've been scripting my job submission process, and in that script I test the exit status of commands like retro-contest submit and retro-contest login. I know in particular that these two commands don't exit with non-zero statuses when errors have occurred, and I believe this issue extends to other commands as well. I know it is only convention, but it is a fairly common convention.

[endrift]

Good call. I'll add this soon.