CLOUD-217 - Added initial EVENT and USAGES RESt resource descriptions
CLOUD-217 added more description to the event and usage REST api
CLOUD-217 organized the resource descriptions
CLOUD-220 implemented draft stack event creation service
CLOUD-220 Corections, added unit test
CLOUD-221 Implemented reactor related logic for persisting cloudbreak events asynchronously. Renamed Classes for better reading
CLOUD-224 Removed history related classes
CLOUD-223 renamed cloudbreakevent related resources to avoid ambiguity
CLOUD-223 Stack status changes fire cloudbreak events. Removed unnecessary service method
CLOUD-225 Draft implementation of the event retrieval
CLOUD-225 added annotations, corrections in the jpql
CLOUD-225 Workaround for null optional parameter
CLOUD-225 Adde new finder to the repository to handle the since parameter
CLOUD-227 Added skeletons for the usage retrieval functionality
CLOUD-225 implemented event retrieval with specifications
CLOUD-225 entity annotated with name
CLOUD-225 enAdded stack id to the event
Merge pull request #281 from sequenceiq/events

lgtm