adding a test matcher allowing to test for absence of a parameter
Initial implementation that enables to specify client id for each hit.
Added client id value seeding that could be used for user UUID generation.
Additional test for seeded client hits.
Added test to check if ClientID was set.
Adjusted counts for async requester test.
Reducing counts for async test.
Detailed messages for failing tests.
Updated docs regarding new client id.
aligning Event's event builder to the style used by other parts of the library
Merge branch 'master' of https://github.com/tasubo/jgmp
improving AsyncHttpRequester test's resiliance against timing issues.

It will now finish as soon as all requests have been executed, but at most 1 second.