Listed valid parameters are based upon values that the EdgeFactory
can accept.

The container is based on the usgs/geomag-algorithms:latest image.

Done to prevent exceptions raised in python 3.6 environment.

Added a class to create error messages and wrapped parse, fetch,
and format_data in try/except statement to catch raised exceptions
and generate error pages.

Also, made changes based on PR revision requests.

Added base class for exceptions and continued work on parsing and
fetching methods.

Need to add more unit tests. Working on usgs/geomag-algorithms#162.