GPII-20: Update GSettings Settings Handler according to the new API

  * Remove "options" block from "get" and "set" return payloads
  * Update gsettingsBridge tests
GPII-20: Update Orca Settings Handler according to the new API

Remove "options" block from "get" and "set" return payloads
GPII-20: Add integration tests for the Flat matchmaker

[Added NP sets]
  * os_common
  * screenreader_common

Both "MikelVargas" and "sammy" NP sets have been commented, so they
aren't being tested.