UMBRELLA: Overhaul climatology.py and test_climatology.py

[hCraker]

Various issues dealing with climatology.py and its test file have been opened. This is an umbrella issue to help keep track of the status of these files.

• Consistent use of unittest #311
• Replace and deprecate climatology and anomaly #265
• CI: nightly tests failing #308
• Add keep_attrs kwarg to all climatology.py functions #314
• Allow user to define seasonal boundaries for climatology_average #198
• add explicit support for numpy.ndarray as inputs

[jukent]

Dev notes for adding numpy support

[jukent]

After much discussion we decided that numpy support will not be necessary in this instance. Since the input requires two variables where one is just the index of the other and outputs two variables where again one is just an index (the new time coordinates are necessary as well as the climatological values), these are not operations that should be done in numpy.