Add markdown resolution error checking to shocco.
Add markdown resolution error checking to shocco.

Also does a bit better job finding the locally installed
Markdown.pl.

Fixes #122

rerun/rerun,stagrlee/rerun,sgoings/rerun,rerun/rerun,stagrlee/rerun,stagrlee/rerun,sgoings/rerun,sgoings/rerun,rerun/rerun,stagrlee/rerun