testExecutionManagerPerformance threshold to 7500ms from 2500ms

- For BasicTaskExeuctionTest.testExecutionManagerPerformance
- Saw 5601ms on buildhive
extract perf tests from BasicTaskExecutionTest

- created BasicTaskExecutionPerformanceTest
- convert that to Java so no overhead/jitter caused by groovy code
jsgui: Replaces calls to getByCid with get.

getByCid was removed in Backbone 0.9.9.
Remove unnecessary callPeriodically in entity-policies.

The callback in initialize() means showPolicyConfig() is called so often
that this callback is constantly overridden and never gets run.
jsgui: Bind 'this' to owning view in functions given to callPeriodically
jsgui policies: Stop propagation of events on policy table.

Means you can click suspend/resume/start policy buttons without toggling
the display of policy config.
Correct typo in AutoScalerPolicy config key description
jsgui policies: Improve display of long policy values
Forgot SimpleMongoDBReplicaSet. Aside: images resized using sips -Z.
Simpify rest project resource tests
Adds an ExceptionMapper to Rest project.

* Sends JSON responses to exceptions.
* 405s (e.g. GET not POST) are still served as Jetty HTML error pages.
* Turns uncaught exceptions into 500 server errors.
Adds StartableMethods.stopSequentially

- And ControlledDynamicWebAllCluster uses it to stop everything, 
  even if stopping the control fails (i.e. continue with cluster next).
Merge pull request #806 from sjcorbett/backlog

Addresses some backlog issues and adds other small enhancements.
Merge pull request #809 from jdtoy/devs-cat-update

Developers Catalog: Missed one.
Handle exceptions with null messages.
Merge pull request #811 from sjcorbett/rest-backup

Rest API error responses
Merge pull request #803 from aledsage/fix/BasicTaskExecutionTest-timesensitive

Fix/basic task execution test timesensitive
Move ApiError class from rest-swagger to rest project.
TypeCoercions throws ClassCoercionException

Rather than ClassCastException. DefaultExceptionMapper in rest project
treats coercion exceptions as bad requests and other cast exceptions as
server errors.
Add optional 'details' field to ApiError

* Serialised as empty string if missing
* Added builder for constructing ApiError instances, with static
  fromThrowable(Throwable) helper
* DefaultExceptionMapper logs throwables at trace.