V0.1.1
- added loading and reloading mechanism for teams and all team data
- queries are now made synchronously because SQLite is always local
anyway (= fast)
  and to make check queries possible immediately after INSERT, UPDATE
and DELETE queries
- team leader may no longer invite himself into his own team or request
membership in his own team
- added commands UNINVITE, LIST [teamName], CLEAR <teamName>