Added wishful test suite for jsonb type
Added name param to register_json()
Add register_default_jsonb() and register the type
Added jsonb docs
Habemus jsonb
Merge branch 'jsonb' into maint_2_5
Document PostgreSQL 9.4 as supported

Actually there is a test failing in the test suite in PG 9.4beta2, but
it's probably because the default logging level is to DEBUG. Will wait
for the final release to check if the test is to be fixed. All other
tests pass no problem.