Issue #2610910: Move taxonomy integration to it's own sub-module

Squashed commit of the following:

commit dd8b9da4c113a5166ad6f72a808b7b25a3c85133
Author: legolasbo <legolasbo@2480548.no-reply.drupal.org>
Date:   Sat Nov 7 15:00:55 2015 +0100

    select_or_other_taxonomy now creates it's own options.

commit 2c6cc2579a87940a3a122d19ebaf16dbc7c9e108
Author: legolasbo <legolasbo@2480548.no-reply.drupal.org>
Date:   Sat Nov 7 00:30:23 2015 +0100

    select_or_other_taxonomy now passes testing.

commit 006b4a782575f141031bcd98590edf8ac23717be
Author: legolasbo <legolasbo@2480548.no-reply.drupal.org>
Date:   Fri Nov 6 21:00:26 2015 +0100

    Other changes from #2598176-16 added

commit 6ab319dca4d39a03f4d1e8a5777b79157058b1b8
Author: legolasbo <legolasbo@2480548.no-reply.drupal.org>
Date:   Fri Nov 6 19:07:27 2015 +0100

    Tests from #2598176-16 added

commit dc59c44b3add5ebaad788d7ab2c0f6a08d10e68b
Author: legolasbo <legolasbo@2480548.no-reply.drupal.org>
Date:   Fri Nov 6 08:28:07 2015 +0100

    Basic extract done. Still needs a lot of bugfixing.