Fix riak-debug and add limits.d gathering

Fixes: basho/riak#325

* Add selinux, system messages, and syslog gathering
* Fix RUNNER_BASE_DIR usage so paths work on devrel and packaging.
* Grab limits.conf and limits.d directory
* Add df inode dump
Merge pull request #326 from basho/bww-riak-debug

riak-debug fixes & additions