Unescape and potentially decode UTF8 in REST paramters

The dispatcher doesn't unescape matched URL values.  Without the
unescaping, it was impossible to use basic REST urls for values
containing reserved characters.

A basic test of functionality is included.  The test file fails before
this commit.
Move unescape to being an internal method
Tests now require width and height on images; placate them
Make the POD spelling test happy