Removed old geodjango suite handling.

These tests are automatically discovered now. Need to add skip
handling for when dependencies aren't met still.
Make django.contrib.tests.geoapp.tests discoverable even if a spatial db isn't installed.
Made gdal tests skip if GDAL isn't available.

These tests don't require a spatialdb or GEOS to run.

If GDAL is installed, skip behavior can be simulated by setting
GDAL_LIBRARY_PATH to a bad path in settings.py.
Made geos tests skip if GEOS isn't available.

Added a HAS_GEOS flag, similar to HAS_GDAL and HAS_GEOIP.

Test skip properly when geos and gdal aren't installed.

If geos and gdal are installed, skip behavior can be simulated
by setting GDAL_LIBRARY_PATH or GEOS_LIBRARY_PATH to invalid values.
Made geoip tests to skip if GeoIP isn't available.
Removed unused imports.
Add HAS_SPATIAL_DB checkout to gis.test.utils.
Made distapp tests skip if requirements aren't met.
Made geo3d tests skip if requirements aren't met.
Made geoadmin tests skip if requirements aren't met.
Made geoapp tests skip if requirements aren't met.
Made geogapp tests skip if requirements aren't met.
Made inspectapp tests skip if requirements aren't met.
Made layermap tests skip if requirements aren't met.
Made relatedapp tests skip if requirements aren't met.
Modified runtests.py to use HAS_SPATIAL_DB rather than the geodjango function.
Remove unused import and extraneous whitespace.