tensorflow based nn

[weiyuehuan]

update tensorflow NN with: 1, latest MC map: mc_v2.1.0 2, consider PMT collection R/Angular dependence. 3, using high static training samples in high R

https://xe1t-wiki.lngs.infn.it/doku.php?id=xenon:xenon1t:analysis:sr1:keras_nn#update2017-12-15_after_telecon

[tunnell]

@pdeperio So we decided to merge without even a basic description of the network, basic checks of the network's fit, nor the code available for producing it anywhere?

[pdeperio]

@weiyuehuan should add everything later. these are just the files for testing, not yet officially called anywhere nor in a release.