Updated JacksonJSONContext to Jackson 2.x and re-added support for 
Jackson 1.x with Jackson1JSONContext
Merge remote-tracking branch 'upstream/master' into branch1

Conflicts:
	cometd-java/pom.xml
now using JUnit's RunWith Parameterized technique to test both
Jackson 1 and Jackson 2 with the same code
removed compiler warning about using raw Collections (List-->List<?>)
now using JUnit's @RunWith Parameterized to test with both Jackson 1 and
2
now using JUnit's @RunWith to test with all available JSON contexts
renamed Jackson Context Server/Client to JSON as we use the Jetty
provider too
now using JUnit's @RunWith Parameterized to test with both Jackson 1 & 2
renamed JacksonJSONContextServer to Jackson2JSONContextServer
renamed JacksonJSONContext, JacksonJSONContextClient, 
JacksonJSONContextServer to Jackson2JSONContext,
Jackson2JSONContextClient,
Jackson2JSONContextClient
removed unnecessary @SuppressWarnings("unchecked")
renamed references to JacksonJSONContextServer to 
Jackson2JSONContextServer
added both Jackson1 and Jackson2 dependencies, added version to
slf4j-simple
renamed references to JacksonJSONContextClient to
Jackson1JSONContextClient
removed forced garbage collection, update references to
JacksonJSONContextServer
heavily refactored to use JUnit @RunWith avoiding duplicate test code
you can now pass the JSON Context as class name or instance consistently
with BayeuxServerImpl
removed Jackson1CustomSerializationTest as now both versions of
Jackson are tested by the same unit test
removed "unused" warnings on the constructors, they need to be declared
in order to be accessible
Travis build failing if I use ${slf4j-version}, trying hard-coding
version