Report Cache Invalidation Locations With DTrace Probe

* Move cache invalidation counts to role
* Add ability to check current process privileges
* Introduce cache invalidation locations role
  * Spawns child process to dtrace parent process
  * Uses method-cache-clear dtrace probe
  * Reports dtrace results
* Add example method-cache-clear.d dtrace probe for use outside Busted
* Update README
report traces data structure should match report invalidations
Better Advanced Usage copy
Child PID is more expressive
remove travis ci config from gem files
Force tracer does not exist, so process privileges can be tested
Force tracer to exist and process unprivileged, so we can test permissions exception
Attempt dtrace install on Travis
Revert "Attempt dtrace install on Travis"

This reverts commit 9ba12b4a1b6ef313faf1b15cb2e13e0941000485.

Try installing dtrace at a later date...
Merge pull request #7 from simeonwillbanks/dtrace-probing

Report Cache Invalidation Locations With DTrace Probe