Made is_url() allow "[-.+a-zA-Z0-9]+:" as a valid scheme and

not reject URLs without a double-slash, as per RFC2068 section 3.2.

Submitted by: Ken Coar, closes PR #146, #187
Reviewed by: Roy Fielding, Dean Gaudet, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77709 13f79535-47bb-0310-9956-ffa450edef68