When running e2e tests on flaky networks, gravatar can cause a timeout
and test failures. Turn off, and populate avatars on e2e test suite run
to make them reliable.
(cherry picked from commit 9ac74a1a408136455a9e0586fb8e65163048597b)
Conflicts:
models/fixtures/user.yml
services/repository/contributors_graph_test.go
trivial context conflicts