bash completion and a smidgeon of error checking

Kyle,

I've added 2 more small changes:

* salticid will warn and exit if no rc files are found (a mistake I made over and over)
* '-x/--explain' which lists the roles and tasks

I also added an extras/salticid-completion.sh which uses '-x' to implement command line completion for bash.

I have no idea what your plans are for salticid or if these changes fit what you want - after seeing you use it at RICON during your live coding I'm going to use it for the same purpose.  Thanks for creating and sharing it.


Kyle