Set the normal DNS resolution again if not restricted explicitely

to IPv6 by IPV4_ONLY setting. Fixes #53
Merge pull request #54 from hynekcer/bugfixes

Fixed #53: Patch IPV4_ONLY now used only explicitely
Removed an unimportant part of test that can not be silenced
Improved auth tests for multiple databases. Test it just now!

Tests for multiple databases require a manual change from now on
in testrunner/local_settings.py: add the second SF sandbox configuration:
  DATABASES = {'default': {...}, 'salesforce': {...}, 'salesforce2': {...}}

The change for testing SALESFORCE_DB_ALIAS is only temporary and must
be tested immediately after this commit because it will be turn back
  settings.py:
    SALESFORCE_DB_ALIAS='salesforce2'

Conflicts:

	salesforce/tests/test_integration.py
Set a central import of "requests" package and use a patched version if possible
Improved raw "select Count() from ", not fixed.