Look over variables with type 'numeric' and change them to 'integer'
when appropriate, which Fixes #7

Adding 'units' to most variables that should have 'units'. Not
entirely finished so will not close #6

Fix a few 'variable' names and 'display_name's
Create a new test to ensure that all 'variables' with 'type' value
'integer' or 'domain' have 'units' AND that the 'units' are valid
units for this data dictionary

Note: Test is used to identify which 'variables' needs 'units'