Expose the search API

[anacrolix]

@barolo

From #10 (comment).

It might be possible to expose the search API over JSON as part of cove, since the rest of it sits idle unless you use it anyway, there's no issue and no need to create a separate project.

[anacrolix]

@barolo: Please try cove v0.4.10 and take a look at https://github.com/anacrolix/dhtsearch.