Added Equipment model and test classes.
Added Equipment to test suite.
Changed Equipment to Instrument.
Renamed Equipment to Instrument
Test the renamed Instrument instead.
Updated tests to be less redundant with the base Model class.
Cleaned up rebase/merge artifact.
Merge pull request #13 from emartinez-usgs/EQH-2138

EQH-2138
Added Observation model and test classes. Included tests in test suite. Updated test suite for linting validation.
Added an ending comment for the constructor test block.
Merge pull request #15 from emartinez-usgs/EQH-2139

EQH-2139
Added User model and test.
Added UserRole model and class.
Added tests for User and UserRole to test suite.
Merge pull request #16 from emartinez-usgs/EQH-2140

EQH-2140 (and EQH-2141)