Fix EntityExecutionManagerTest

- Failed in jenkins with “wrong” tasks being GC’ed.
- Aled speculates the two tasks terminated in the same millisecond,
  so introduce small delay between tasks and also log more info about
  tasks on error.
DynamicCluster: ensure cause of resize error is reported
Add TestApplication.newSimulatedLocation()
Bump TomcatServer version to 5.0.56
TestJavaWebAppEntity: tidies
TomcatAutoScalerPolicyTest: code tidy
Use Duration for AutoScalerPolicy.builder methods

- instead of taking long, take Duration parameter.
- for minPeriodBetweenExecs, resizeUpStabilizationDelay,
  resizeDownStabilizationDelay, and maxReachedNotificationDelay.
- Test tidy (for use of deprecated methods)
Fix Solr version number

- and uploaded solr-4.7.2.tgz to
  developers.cloudsoftcorp.com/brooklyn/repository/SolrServer/4.7.2/solr-4.7.2.tgz
Asserts: log.info with details of failure
BrooklynMavenArtifactsTest: allow retry for URL

- have seen response code 500 from repository.apache.org for snapshot
  builds, so retry for default timeout (30 seconds)
This closes #275