btag code cleanup 

Cleanup of the btag code that includes the following updates:

 * configuration files use more consistent naming convention for different modules and taggers. In addition, the cff and cfi file guidelines described in https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideAboutPythonConfigFile are now followed more closely

* updated MVA computer so it ignores any extra TaggingVariables in case they are provided by the jet tag computer

* removed extra instance of the CSV computer now that the MVA computer has been updated

Some validation plots are attached:

**TCHE**
![performance_tche](https://cloud.githubusercontent.com/assets/4885289/4960600/c2b86e46-66c4-11e4-920d-26afaa137dbb.png)

**CSV**
![performance_csv](https://cloud.githubusercontent.com/assets/4885289/4960604/cc3a72c0-66c4-11e4-9173-24fad70a2b24.png)

**CSVv2+IVF**
![performance_csvv2](https://cloud.githubusercontent.com/assets/4885289/4960607/d65048ca-66c4-11e4-9c55-59faaf51c91a.png)

The only plot showing small changes is the CSV one which is expected because of updated `maxDeltaRToJetAxis` vertex cut from `0.5` to `0.4`. CSVv2+IVF is not affected since there is an additional `extSVDeltaRToJet` cut set to `0.3` so the above  `maxDeltaRToJetAxis` change does not affect IVF vertices.

This PR supersedes #6261