Adds support for CRS temporal and spatial standards codes.

Adds a temporal code and EPSG code to the CRS parameters.
Adds test coverage for CRS code updates.
Merge pull request #48 from oceanzus/crs_updates

Adds support for CRS temporal and spatial standards codes.
Adds new files supporting the refactored nosetests framework.
Adds time axis to 'time' parameter.
Continues migration from test_coverage_basics.
Continues migration from test_coverage_basics.

Replaces uppercase parameter names to lowercase in tests.
Comments out migrated tests in test_coverage_basics.
Removes working directory if exists.
Completes migration from test_coverage_basics.py

test_slice_and_dice omitted from tests due to suspected duplication with test_get_by_slice.
Adds get_props decorator function

Adds get_props() decorator function and TESTING_PROPERTIES class dictionary to enable subclasses to provide properties on a class-wide and test-by-test basis.  This allows the tests defined in CoverageIntTestBase to remain generic and flexible.
Adds tests and minor cleanup.

Adds test for checking the list_parameters() function.
Refactors assertions using SimplexCoverage to AbstractCoverage.
Adds override for empty coverage test.

Added override for test_get_by_slice.
Adds coverage for _axis_arg_to_params.
Moves CRS tests to coverage_test_base.py
Adds ViewCoverage tests.