don't cache the proxy url

It changes each time the test starts a new proxy
Fix tests from error message changes introduced in 9d2106
test renewal in integration test
The daemon process is now started as an exec()

The integration test needs to start to client/daemon pairs to test a contended
claim.  When the second daemon started up, the still-running client-side watcher
created when the first daemon ran was responding to requests in the second daemon's
process.
add integration test for a waiting claim
test server dropping responses during activate
test server dropping responses during renewal
include the offending resource in the error message for fatal errors