Fix b tag bug in top hlt dqm offline and validation codes

In PR #3457, several EDProducers and EDFilters have been removed, breaking the Top PAG HLT DQM Offline code. The plots produced for validation in CMSSW_7_1_0_pre7 are therefore empty. This PR fixes this problem and need to be merged ASAP to make the validation anew possible.
The occasion is also taken:
- to change the names of the GUI directories to be finally able to use RelMon
- to start the migration from ak5 to ak4 (b tagging being available only for ak5, everything can't be migrated)