test: GDrive tests are getting skipped.

[skshetry]

As the title says, tests for GDrive are getting skipped on travis.

[shcheklein]

@Maxris JFYI

[efiop]

should_test is checking for GDRIVE_USER_CREDENTIALS_DATA but I don't see it in .travis.yml nor in travis env vars tab. But I do see OAUTH env vars in travis env tab. CC @Maxris

[efiop]

Looks like need to create setttings.yml for PyDrive https://gsuitedevs.github.io/PyDrive/docs/build/html/oauth.html and use our dvc-test project's creds.

[maxhora]

It was supposed to set encrypted GDRIVE_USER_CREDENTIALS_DATA in Travis configuration for DVC repo under Iterative's account. I should give update later today on this.