Tasks to make fermipy easier to manage

1. Separate out the diffuse emission and isotropic emission models
   
   1. These currently live in a conda package
   2. They are generally available at SLAC via GLAST_EXT, we probably want to combine the two methods of getting them
2. Split out the sub-modules
3. Develop a template for a user contributed package

Template for a user contributed package

This should include, at a minimum a setup.py file, but could include a number of things such as 

• Template for documentation
• Template for connection to continous intergration system such as travis or azure
• Template for connection to coverage tests, such as coveralls
• Template for connection to documentation system such as read the docs
• Template for containerization

Science Related Development Projects

• Standardized ROI analysis and control tests (fermipy.jobs module)
• Standardizes stack analysis (fermipy.stack module)
• Handling energy dependent pixel sizes for TS map creation.
• Integration of weights map creation
• Handling of all-sky maps and analysis model components (fermipy.diffuse module)
• Create of models based on source populations
• Light-curve creation