Added ban robustness

a few issues came up with this:
1) TSServerPlayer had no useraccount name.  I have added this is a hardcoded constant, and have prevented /register from using that string.
2) The release build of terraria server api (and the one currently in the repo) shit itself while I was trying to use it today.  It is extremely weird and I have no clue why.
3)This enables the usage of the new fields, but no actual in game mechanic allows for setting expiration.  We will need to figure out how to handle this, either by making a parsable string like 1M1d1h1m1s or something.