fix 500 response if regex control chars in path param
fix 500 response if regex control chars in path param

Client-provided variable should be escaped before in use for regex. Leads otherwise to syntax errors if it results in an invalid regex, e.g. `/docs?path=foo(`

Credit for escape regex to bobince on http://stackoverflow.com/a/3561711/134162

glennjones/hapi-swagger,glennjones/hapi-swagger,edimoldovan/hapi-swagger,ruionwriting/hapi-swagger,glennjones/hapi-swagger,edimoldovan/hapi-swagger,ruionwriting/hapi-swagger,glennjones/hapi-swagger,barryhammen/hapi-swagger,barryhammen/hapi-swagger