Half finished PR/PW test
Change PR/PW test to use intercepts instead of kill -STOP

Thanks to @rzezeski for the help with intercepts
Add missing function
Actually make the intercepts work...
Add http client test and dw_val_unsatisfied tests

Add an alternate vnode intercept, one that returns failures, rather than
simply never responding.
remove unnecessary underscores
use more rt-built-in goodness

rt:build_cluster, rt:http_url, rt:stop_and_wait, and rt:start_and_wait
Merge pull request #218 from basho/adt-pr-pw-test

Test for PR/PW