Implement "add all" command in AdminUserHandler
Add "auth" Command for SteamGuard

This removes the dependencies on a GUI for auth code input and gives
a more admin-friendly method of steamguard auth.

May not be a perfect solution, but things such as threading
problems are unlikely to happen due to the sleeps and very little
write activity.
Remove Unneeded Form
Merge pull request #268 from kxsong/kxsong

Implement "add all" Command in AdminUserHandler
Merge pull request #274 from Lagg/guiless

GUI-less
Added TradeEventType enum

poll() now uses TradeEventType instead of integers.