Review possible run-time configuration parameters to add to config_run.yaml

[chriska85]

In the current version of OpenEMPIRE the config_run.yaml file only includes a hand-full of the possible configurations one can imagine using for optimization runs. As of now the user has to interact with the model through the excel input files to run sensitivity analysis, however, some configurations (e.g. enabling/disabling technologies for investment and level of transmission expansion permitted) could easily be changed upon run-time if the configuration file allowed.

Also, more general settings could be added to config_run.yaml,, e.g. optimization solver settings and log level which are currently hardcoded in Empire.py.

We should review and restructure the files config_run.yaml, run.py and Empire.py to improve flexibility in model run.