Added support for Hosted Management Center.

This is done by adding the projectid/securitytoken setting to the ManagementCenterConfig
and by updating the ManagementCenterService to make use of these settings correctly.
Added the Demo Application
Added the XML functionality for the extra ManagementCenter config options
Minor tweaks in the xml parsing
More tweaks in XML parsing url
Additional debug logging
Added a test for TimedMemberStateSerialization
Removed the security token from the start.do url
Added standard way to transform Future to CompletableFuture
Lowered synchronized area
Added direct CompletableFuture to the ExecutionService calls
Now all returned Futures are CompletableFutures
Removed synchronized blocks to atomic reference updates
Resolved mor sonar issues
Merge pull request #1483 from pveentjer/improvement/3.x/sonarissues

Resolved more sonar issues
Playing with excludes to increase test coverage
Merge branch 'master' of https://github.com/hazelcast/hazelcast
Added support for Hosted Management Center.

This is done by adding the projectid/securitytoken setting to the ManagementCenterConfig
and by updating the ManagementCenterService to make use of these settings correctly.
Added the Demo Application
Added the XML functionality for the extra ManagementCenter config options