Don't use escapeshellcmd

We are already escaping the arguments using escapeshellarg.  The rest of the command is hand crafted and not exposed to user input.

Using escapeshellcmd was escaping `?` in URIs, resulting in bad results from pa11y.
Merge pull request #6 from mfairchild365/command-problems

Don't use escapeshellcmd (fix bad results from pa11y)