Removed many calls to flea.TestAgent from the test suite

This is the first stage of a plan to remove the testing
dependency on flea.
We only rely on a tiny part of its functionality and it brings in a
dependency on lxml, which is fairly heavyweight.
In most cases it can be replaced with call to app.requestcontext().
Stash the entire RouteTraversal object in the context

In this way all information generated during route traversal information
becomes accessible to applications