Added URL fetcher interface.
Added Wget implementation of UrlFetcherInterface and a test for UrlFetcherInterace.
Changed the name of the class from Wget to Curl.
Added a brokenUrl flag.
- Added TODO reminder to implement a pure Java class for this interface.
- Added 'get' to url() and source() to follow project conventions.
- Beefed up some comments.
Fresh start.