wifiblaster: allow measurements to be triggered.

- Add the ability to trigger measurements outside of the automated
  scheduling.

- Trigger a measurement whenever a client associates.

- Add a 'measureall' parameter to measure all clients, replacing
  'rapidpolling'. Unlike 'rapidpolling', which increased the measurement
  frequency and relied on the automated scheduling to measure all
  clients, 'measureall' immediately measures all clients in succession.

Change-Id: I8a75cee66f268161391ca15bd5af6718d7e69913
2 files changed