Updated README and package as long_description

[duncanmmacleod]

This PR updates the README, and patches setup.py to include the README contents as long_description (for pypi).

[coveralls]

Pull Request Test Coverage Report for Build 21

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage remained the same at 100.0%

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Files with Coverage Reduction	New Missed Lines	%
gwtrigfind/test_trigfind.py	1	99.07%
<!--	Total:	1		-->

Totals
Change from base Build 20:	0.0%
Covered Lines:	267
Relevant Lines:	267

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💛 - Coveralls