Add launch hidden option
Created by: MadLittleMods
Fix https://github.com/gitterHQ/desktop/issues/107
Based off of https://github.com/gitterHQ/desktop/pull/154
- Renames
startHidden
tolaunchHidden
which matches up with the "Launch on startup" language on the other option.
Tested on Windows 10 on startup and launching normally
cc @nicolas33