Switching default tau MVA input to ConfDB

Having moved the tau payloads to the production database, tau sequence is switching input for all its MVA discriminators and at the same time removing the root files from the CMSSW. The former behaviour can be restored by
1) re-including the root files
2) adding the 2 lines below to the config python to swich the input
```
from RecoTauTag.Configuration.switchMVAtoDB_cfi import switchMVAtoDB
process = switchMVAtoDB(process)
```
@andrew314
@veelken