Bug Fix #1: Incorrect URL error when URL is actually correct.

I recently fixed a bug which caused the system to report a valid URL as invalid.

When the PDX After School server tests a URL to check whether it is valid, it tries to access the page, then it checks whether a web page is returned. Some web sites do not allow anything other than a common browser to access their content. Common browsers use a description to identify themselves, called a user agent string. In order to fix the problem, I set PDX After School to provide a user agent string to identify it as a browser when it checks URLs.