Make E2E tests more site-specific

Also allow a single testConstants.json change (changing three lines in
total) to drive everything: protractorConf.js, setupTestEnvironment.php,
and anything else. This allows the Ant build file to drive the change,
and set the appropriate test settings for the TeamCity build environment
as well as for developers' environments.

Additionally, moved the Activity Page E2E test from the bellows/ folder
to the scriptureforge/ folder, since it has a lot of SF-specific
assumptions in it. Once it can run on either SF or LF without errors, it
can be moved back into bellows/.