bulk upload completed Fixes #30
do not store measurement refs in track
Merge branch 'origin/dev' of into dev
seperated encoders and decoders
added todos for #35
delete track references on measurements
remove user references on delete
cleaned statistics dao dependencies
more efficient user removal
Fixed #36: Incorrect removal of friends
compared wrong media type
removed unnecessary factory bindings
configuration options for input/output validation
404 for users that are not friends
Merge branch 'dev'

* dev:
  404 for users that are not friends
  configuration options for input/output validation
  removed unnecessary factory bindings
  compared wrong media type
  Fixed #36: Incorrect removal of friends
  more efficient user removal
  cleaned statistics dao dependencies
  remove user references on delete
  delete track references on measurements
  added todos for #35
  seperated encoders and decoders
  do not store measurement refs in track
  bulk upload completed Fixes #30