JCLOUDS-156: Cleanup Abiquo provider

Removed legacy and trivial code from the Abiquo provider:

* Removed all trivial predicate classes.
* Removed all find* and list* methods in the domain objects that did
  nothing but delegating to Guava Iterables.
* Removed UCS and Pricing Apis, since they are out of the scope of the
  provider.
* Moved monitor events to the existing monitor package.