integrate btdigg search api

details on frostwire-desktop repo ([PR #376](https://github.com/frostwire/frostwire-desktop/pull/376))
ok i wasn't sure where to put documentation there is another similar file ive added to the frostwire-desktop repo i will remove also - this file will be very helpful to have around tho - i just made a comment about documentation and refactoring of these classes on the PR #7