Merge branch 'develop_integration_2019_w21' into 'develop'

See merge request oai/openairinterface5g!595

The following Merge Requests are included:

* MR 544: RRC Inactivity Timer testing
* MR 581: Remove deprecated build options
* MR 583: RRC: add an option to enable measurement reports
* MR 590: bugfix UE realtime bug