Implements flat line check
Use numpy.testing functions in tests
Fixes location distance calculation

Fix distance calculation to use pyproj.  Optionally also accept
different units for the distance threshhold.
Merge pull request #10 from benjwadams/add_flat_line_test

Implements flat line check
Merge pull request #11 from benjwadams/fix_distance_calcs

Fixes location distance calculation
Added previous QC application to remaining checks
Merge pull request #15 from benjwadams/add_prev_qc

Added previous QC application to remaining checks
Renamed PrimaryFlags to QCFlags
Merge pull request #14 from benjwadams/rename_primary_to_qc_flags

Renamed PrimaryFlags to QCFlags
Added attenuated signal check (QARTOD Test 10)
Merge pull request #17 from benjwadams/add_attenuated_signal_check

Added attenuated signal check (QARTOD Test 10)