JOSS release

This release is for publication in JOSS, with some major changes which includes but is not limited to:

• renaming of the package from exotic-ism to exoticism
• include setup.py to make it installable
• set up CI and write some initial tests
• include code of conduct, contribution guidelines
• prune limb darkening data files and reorganise data
• add white and red noise calculation
• write out PDF report with each data analysis run
• include grating G280