Fixed typo in docs request.cookies -> request.state

https://github.com/hapijs/hapi/issues/1868
Merge pull request #1869 from raffi-minassian/master

Fixed typo in docs request.cookies -> request.state
Switch nipple to wreck. Closes #1871
Merge branch 'master' of github.com:hapijs/hapi
6.6.0
Allow agent to be set on proxy options and passed into Nipple.
Add parallel: false parameter to test case.
Call done() within nipple mock.
Formatting fix
Update doc with agent option