Fix MemoryUsageTrackerTest

- was non-deterministic (asserting memory usage immediately, before
  listener had been called by GC)
Fix feed rebind

- Was expecting xpath /feed/id, but was
  /brooklyn.entity.rebind.dto.BasicFeedMemento/id
- Changed XmlMementoSerializer to use “feed”
- Integration test failing was NginxRebindWithHaIntegrationTest.testChangeModeFailureStopsTasksButHappyUponResumption
Fix yaml use of SshCommandSensor

- Was causing failure of VanillaBashNetcatYamlTest
- SshCommandSensor constructor expects ConfigBag, rather than Map.
- Change BrooklynYamlTypeInstantiator.newInstance to look for a
  <init>(ConfigBag) constructor as well.
- Fix `Class AddSensor.getType("String")` so it tries prepending
  "java.lang." as well
- set poll period to 100ms in yaml (instead of default 5 minutes)
Fix SshCommandIntegrationTest

- Change sensor period to 100ms, from default 5 mins.
  Otherwise if first poll happens before serviceUp=true, it will
  timeout in 30 seconds without a second poll.
Fix HttpRequestSensorTest.testHttpSensor

- Change sensor period to 100ms, from default 5 mins.
  Otherwise if first poll happens before serviceUp=true, it will
  timeout in 30 seconds without a second poll.
BROOKLYN-83: fix SensorResourceTest

- On getting a sensor, if no "Accepts" header is given, then we don't
  control whether json or plain text comes back.
  It is dependent on the method order, which is compiler-specific.
- Therefore delete the test that gave no Accepts and then asserted
  it was json.
BROOKLYN-85: fix FixedListMachineProvisioningLocationTest