code-cleaning in RecoMET/METProducers/python

This PR deletes old definitions of CaloMETs, which were replaced with new definitions at https://github.com/cms-sw/cmssw/pull/3942.

This PR also deletes aliases, which became optional at https://github.com/cms-sw/cmssw/pull/4006, from several MET definitions.

(this refers to all)
Does it make sense to remove aliases for common names completely?
Some analysis scripts in fwlite rely on these.
What's the strategy now? Let people set the aliases manually?
```pfMET.phi()``` is much simpler to use in fwlite tree draw than the full branch name