Reading JER

Currently we read JER from the GT.

We should add support for reading from a local file

EDIT:
e.g.
```c++
if( jerFromFile_ == true ){
resolution_ = JME::JetResolution(resFile_);
resolutionSF_ = JME::JetResolutionScaleFactor(resFile_sf_);
```
in the constructor of `ntp::userdata::JetUserData`