updated user service and gui when user disconnects. fixed some bugs

Ignore-this: 463b66ad432c263c7820ac6a8c2db85a

darcs-hash:20130427183753-c21fe-3d8536364e2360c1e4b578fe2e035550ba8831c7
turned off retries in TCP connections that fail. this slowed down local network connections when connecting to a greeter failed

Ignore-this: e9320a8bcfa9841d37dd4cdf3cce846b

darcs-hash:20130427183915-c21fe-0a0a8355568c3538558558a6043b0947871de8fa
changed to hash map for contact_list

Ignore-this: a4e87be2bab1bfc65d452b1cca646feb

darcs-hash:20130427183955-c21fe-18b136683f6afe8923f415ac7b91256010dbecac