Gatorgrade

Support the creation of a report in either the Markdown or JSON formats. These reports can be saved to a file or to an environment variable. If you save them to an environment variable like
The file config/gatorgrade.yml either does not exist or is not valid.
Exiting now! then it will create a GitHub job summary that students may find convenient to consult.

Make a small change to the check_result module to change the symbols used to show when a check is correct or incorrect.

Since the generate command does not have all of the features it would need to be fully useful, remove it from the command-line so as to avoid confusion.

Ensure that GatorGrade does not crash when the --config parameter points to a missing configuration file.

Return non-zero return codes when the use of gatorgrade fails.

This release adds support for shell checks and improvements to the output.

What's Changed
* Execute shell checks and improve output by mariakimheinert in https://github.com/GatorEducator/gatorgrade/pull/91
* Touch up the README by mariakimheinert in https://github.com/GatorEducator/gatorgrade/pull/92


**Full Changelog**: https://github.com/GatorEducator/gatorgrade/compare/v0.1.0...v0.2.0