Add Vars to tox that are needed to get tests to start running.

tox.ini

@@ -30,7 +30,9 @@ passenv =
     BOK_CHOY_HOSTNAME
     BOK_CHOY_LMS_PORT
     BOKCHOY_HEADLESS
+    DISABLE_COURSEENROLLMENT_HISTORY
     DISPLAY
+    DJANGO_SETTINGS_MODULE
     EDX_PLATFORM_SETTINGS
     EDXAPP_TEST_MONGO_HOST
     MOZ_HEADLESS
@@ -45,11 +47,13 @@ passenv =
     SELENIUM_PORT
     SHARD
     SKIP_NPM_INSTALL
+    SSH_AUTH_SOCK
     TARGET_BRANCH
     TEST_SUITE
     XDIST_GIT_BRANCH
     XDIST_GIT_REFSPEC
-    XDIST_NUM_TASKS
+    XDIST_INSTANCE_TYPE
+    XDIST_NUM_WORKERS
     XDIST_REMOTE_NUM_PROCESSES
     XDIST_WORKER_AMI
     XDIST_WORKER_IAM_PROFILE_ARN