Riak bugfixes

Here's a quick summary of stuff, separated by commit.

1)
I've made some changes to the way the stats stuff is collected.  Originally it would try to poll the riak stats at http://ip/stats:8098 and then fall back to running riak-admin status.  I've simplified it:

Now it will attempt to poll http://ip/stats:8098 in a loop for 120 seconds (it really should never take this long, all of my work shows it coming up immediately), and if it takes longer than that, the module will fail.

2)
Additionally I've made changes to the wait_for_handoffs and wait_for_ring, so that you can specify an integer in seconds rather than a boolean in the playbook.