Disable imagemin task

- CI build and few other platforms have failures running this task.
Hence, disabling it and copy the images directly into dist.
Fix package tangle

- Move StreamFactory from org.springframework.xd.dirt.core to org.springframework.xd.dirt.stream
Fixed issue with stream/job undeployment

When undeploying a stream/job the stream/job definition is loaded
in order to perform a graceful undeployment of the underlying
modules. However if the stream/job definition has already
been removed from /xd/streams|/xd/jobs then the definition
cannot be loaded. This fix will prevent an attempt to read
a definition that has been removed.

Test improvements, improved JSON parse error

AbstractSingleNodeStreamDeploymentIntegrationTests.moduleChannelsRegisteredWithMessageBus
will fail fast if module deployments fail.

Ensure that thread interrupt is honored in SingleNodeIntegrationTestSupport.waitForStreamOp.

MapBytesUtility will include an improved JSON parse error message.

Bug fixes

Fixed issue with admin server using cache of /xd/deployments/streams
to read stream definitions instead of /xd/streams.

Fixed issue where admin server was always assuming that
/xd/streams/stream-name was always expanded (implying that
all streams are deployed).
using StreamCommandListener in integration tests
avoid race condition for deploy/undeploy events
Obtain stream list from deployments path

When a new container joins the cluster the admin will determine
if a module should be deployed to it. This change ensures that
only deployed streams will have their modules considered for
deployment.
XD-1481 - Remove spring-xd-analytics-ml-pmml project

Removed from the build.
Updated spring-xd-analytics-ml with implementation/tests in https://github.com/thomasdarimont/spring-xd/tree/feature/XD-1420