remodeled sensor
remodeled sensors close #47
Merge branch 'dev' into sensor

* dev:
  throw 409 for already existing mail addresses (fixes #52)
  reversed sort order for activities (fixed #11)
  HTTP Basic Authorization
removed obsolete classes
filter sensors by type (see #42)
allow arbitrary maps as sensor properties
abilitiy to parse arbitrary sensor properties
generic filters for sensor attributes (closes #42)
do not modify query parameters
Merge pull request #53 from car-io/sensor

Merge sensor changes