GPII-114_FLUID-4852: Added configs for get'ing and set'ing escaped elpaths as used for model transformation

This is a pre-requisite for removing duplicate definitions from the GPII code. I created GPII-114 for this. Not sure to what extend this also takes care of FLUID-4852, or whether this JIRA was though to be integrated as default behavior as opposed to seperate configs.

JIRAs in question:
http://issues.fluidproject.org/browse/FLUID-4852
http://issues.gpii.net/browse/GPII-114