Renamed App 'invoke' method to 'enqueue'.
Service port range configuration.

Instead of binding on randomly picked ports, the runtime will now keep
an ordered list of configured ports and pick them one by one for all the
new services.
Fixed a GCC 4.4 build issue.
Properly stop the services.

Services are now being terminated inside the locator, so no need to
terminate them again in other places.
Report port configuration on start.
Changelog bump.
Log wording.
A forgotten lock in Locator implementation.
Changelog bump.
Typo.
Fixed a deadlock in Locator.
Proper variable naming.
Huge source files has been splitted.
Hide some more implementation details.
Bump the release version.
Drop some unused code.
Cleanup.
Port ranges are now optional.
Proper variable naming.
Properly handle MessagePack errors.