Removing uber classloader

As there's no need for it
Fixing taskType

It must be FQCN now
Giving some time for TPSPI

Also, hinting some messages for logging
Move code and share it

To not have it littered in multiple places
Conversion mistake

In old api "cancel" was also REMOVING the task.
Fixing wait resource

As now DONE tasks are there too, so the sole presence of
"now" schedule does not means something is still running.
Tasks are not in nexus.xml anymore.

Doing assertions against REST instead of nexus.xml contents.