* adds team sharing field to share form
* splits sharing logic into user based and teams based
* adds TeamAdmin for admin backend
* adds validity check on Team name -> only unused names shall be valid
* removes admin backend views which are not important for production
* adds filtering functionalities on index views
* simplifies detail views on intervention, compensation, ecoaccount and ema
* adds autocomplete fields on detail views
* adds handy horizontal filter fields on detail views
* adds UserActionLogEntry model to user/models.py
* wraps user and timestamp info
* can be extended for more information in the future
* refactors all filtering and accessing on values
