Functional tests stop running without error or termination

[oliverroick]

Functional tests intermittently stop running, without any error or explicit termination. I've seen this both on Travis builds and locally.

Examples:

.tox/py35-functional-batch3/lib/python3.5/site-packages/cadasta/test/record_tests/test_tenure_relationship_creation.py::TestTenureRelationshipCreation::test_user_can_create_custom_rel_with_new_conditional_individual 
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated

.tox/py35-functional-batch2/lib/python3.5/site-packages/cadasta/test/project_tests/test_browsing.py::TestBrowsing::test_org_member_can_see_all_org_projects_on_projects_lists 
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated