Bump default Riak version to 1.4.0.
Updated vm.args with new default arguments.
Updated app.config with new default arguments.
Add alternate method of setting ulimit for Debian due to start-stop-daemon
bypassing PAM.
Target version 2.2.4 and above of the yum cookbook because earlier
versions contain a broken broken test stub that breaks test-kitchen.
Merge pull request #78 from basho/hc-riak14

Bump default Riak version to 1.4.0.