AK5 to AK4 for JEC's, Redux

Update of PR #5299, including suggestions from @Martin-Grunewald and
@mmarioncern. 

Here is the last expected change for the AK5 -> AK4 transition. The
AK4 and AK8 global tags are now present at RECO and HLT level. I have
moved the defaults from AK5/AK7 to AK4/AK8 now. I also added services
for ALL available payloads (AK1,2,3,...10). The "default" is AK4. 

I have coordinated with JME Trigger contacts to include the requisite
changes to CondDB for the HLT-related software changes. However, this
will still break the Run 1 matrix tests (5.1 and 25.0) with this
current PR. 

Additional changes were made to fix unit tests by changing the global
tag from "startup" to "run2_mc", which fixed the broken unit tests. 

Tested on the following workflows :
- Working : 4.22, 4.53, 8.0, 1000.0, 1001.0, 1341.0, 25202.0
- Broken : 5.1, 25.0

Automatically ported from CMSSW_7_2_X #5350