In the RPC server, have the "status" method return the logs from the last compile

[beckjake]

Describe the feature

In #1699, I added a feature where a SIGHUP causes the RPC server to recompile the manifest. Unfortunately, it just keeps shoving the logs to stdout/dbt.log. Instead/additionally (whichever is easier) it should make them available to the 'status' method under a 'logs' key.

Describe alternatives you've considered

We could just keep dumping them to the regular logger

Additional context

N/A

Who will this benefit?

RPC clients