Updated the banning system(Changes and fixes)

*Fixed the edit ban window trying to start/update on players who are not
on the server.
*Fixed a bug with servers that have more then 200?+ bans, with some
players not being banned due to a bug with banid command. I didn't find
this my friend ChuteUK did but since I'm doing updates I figured I would
throw this in.
*Added FAdmin.IsSteamID, because it looks cleaner.
*Added Checks when the unban command is run to see if its a vaild
steamid/if the steamid is currently banned.
*Added a search box on the unban menu
*Changed ValidPanel to IsValid