First step on implementing H2 storage
Minor, fixed not imported class
Cleaned MessageStore interface to avoid duplication of methods used in couple. Switched from guid + message to move messages
Separated ISubscriptionsStore from ISessionStore
Implemented H2 queue
max line length warnings removed
missing Copyright added
useless publics removed
unmaintainable Javadoc tags: @author removed
helper class warnings removed
field default value initialization removed
Multiple warnings removed
pref: checkstyle warnings removed
Checkstyle will fail the build process if it detects violations
switch default cases error logger added