Events should be enabled automatically when logging in via live API.

If events are not enabled for example originate will not work as it is
implemented via events.
ChannelManager: add support for waiting for channels to appear.
AsteriskServerImpl: await the originated channel to become available.

Previously the #originate(OriginateAction) might had failed every time on 1.8
or randomly as the channel was not ready to be found using #getChannelById
when the OriginateResponseEvent was processed. The extra 2000ms timeout can
now be removed.
ResponseEventsImpl: fortify #events for multithreaded access

Previously events were synchronized only when adding new events, but
never for iteration.
ManagerConnectionImpl: sendEventGenAction: simplify cleanup, wait inside loop

There was copypasted listener removal code in two separate paths, fixed.
Also the response gathering wait was done without a loop, resulting in not
actually waiting anything if there had been a spurious wakeup.
HangupEvent: add missing properties (1.8)
Merge branches 'originate_fix_async' and 'master'
Fix for AJ-198
Merged koivunej/asterisk-java/master
Updated to current SLF4J version
Fix for AJ-320
Handle ManagerError correctly in originateAsync
Fixed CdrEventTest