Adding v2 for API

Instantiating a second version for the API.  For now, it's identical
to v1, but can be customized as needed in the future.

config/settings/base.py

@@ -336,7 +336,7 @@ REST_FRAMEWORK = {
         'api.versioning.NestedNamespaceVersioning',
         #'rest_framework.versioning.NamespaceVersioning',
     'DEFAULT_VERSION': 'default',
-    'ALLOWED_VERSIONS': ['default', 'v1'],
+    'ALLOWED_VERSIONS': ['default', 'v1', 'v2'],
     'DEFAULT_PAGINATION_CLASS':
         'rest_framework.pagination.LimitOffsetPagination',
     'PAGE_SIZE': 1e7,

gracedb/api/urls.py

@@ -5,5 +5,5 @@ app_name = 'api'
 urlpatterns = [
     url(r'^', include('api.v1.urls', namespace='default')),
     url(r'^v1/', include('api.v1.urls', namespace='v1')),
-    #url(r'^v2/', include('api.v2.urls', namespace='v2')),
+    url(r'^v2/', include('api.v2.urls', namespace='v2')),
 ]

gracedb/api/v2/events/fields.py

+from ...v1.events.fields import *

gracedb/api/v2/events/tests/mixins.py

+from ....v1.events.tests.mixins import *

gracedb/api/v2/events/throttles.py

+from ...v1.events.throttles import *

gracedb/api/v2/events/urls.py

+from ...v1.events.urls import *

gracedb/api/v2/events/views.py

+from ...v1.events.views import *

gracedb/api/v2/fields.py

+from ..v1.fields import *

gracedb/api/v2/filters.py

+from ..v1.filters import *

gracedb/api/v2/main/views.py

+from ...v1.main.views import *

gracedb/api/v2/mixins.py

+from ..v1.mixins import *

gracedb/api/v2/paginators.py

+from ..v1.paginators import *

gracedb/api/v2/settings.py

+from ..v1.settings import *
+
+API_VERSION = 'v2'

gracedb/api/v2/superevents/filters.py

+from ...v1.superevents.filters import *

gracedb/api/v2/superevents/paginators.py

+from ...v1.superevents.paginators import *

gracedb/api/v2/superevents/permissions.py

+from ...v1.superevents.permissions import *

gracedb/api/v2/superevents/serializers.py

+from ...v1.superevents.serializers import *

gracedb/api/v2/superevents/settings.py

+from ...v1.superevents.settings import *