rpcserver: Add median time to verbose results.

[JoeGruffins]

Median time is a useful value to return to clients, saving them the
trouble of calculating it themselves. Include the value in verbose
getblock and getblockheader results.

closes #2637

[davecgh]

Thanks for the PR. This looks pretty good overall. Just a couple of inline comments.

[rstaudt2]

Looks good to me, I tested getblock and getblockheader, and they worked as expected. The JSON RPC API docs should probably also be updated to include the newly added field.

[davecgh]

The JSON RPC API docs should probably also be updated to include the newly added field.

Good call. Agreed.

[JoeGruffins]

Will update the docs.

[JoeGruffins]

Added to docs/json_rpc_api.mediawiki in two places. I think that's sufficient?

[JoeGruffins]

With the internal help, all phrases start with a lowercase "the" and end with a period. In the docs, they start with a capitalized "The" and have no ending punctuation. Just wanted to say that out loud.

[davecgh]

Added to docs/json_rpc_api.mediawiki in two places. I think that's sufficient?

Yes, the changes look good. One for each of the two modified results.

With the internal help, all phrases start with a lowercase "the" and end with a period. In the docs, they start with a capitalized "The" and have no ending punctuation. Just wanted to say that out loud.

This is correct. They both follow the standard practices for their respective function. Namely, the help output follows standard JSON-RPC practices while the API documentation follows standard API docs practices of using full grammatically-correct sentences.

[davecgh]

Approval with JSON-RPC API documentation updates.