hotfix for audit integration
bumped version to 0.1.20
Merge branch 'release-0.1.20'

* release-0.1.20:
  bumped version to 0.1.20
  added auditing errors in population
  added duplicates heck for questionnaires collection
  added support for maintenance page
  removed unused code, will be used for auditing
  updated status page to use db wrapper
  updated to use databse wrapper
  changed to bulk population to speed up the process
  updated building device inventory to use database wrapper
  more descriptive errors in gcm_server.py
  hotfix for deanonymization of Bluetooth
  database wrapper updated to use configured databases for different probes
  task for deactivating the authorizations with facebook token that expired
  notifying users about expired facebook authorizations using gcm registration
  bumped version to 0.1.19-devel
  hotfix for audit integration
bumped version to 0.1.20-devel