Bug 947563 - [Settings] Wifi hotspot settings...

...prevent users pressing OK w/o any error messages.

 - Removed password field in internet sharing panel.
 - Move security section before password.
 - Add password desc displayed when security option is NOT "open".
Merge pull request #14893 from joshthecoder/bug947563

Bug 947563 - [Settings] Wifi hotspot settings... r=crh0716