R1:ee6c24b98d1a

Add two new conduit methods: createlintresults and getdiffproperty

Summary:
We need createlintresults because we are doing extended
static analysis offline, and thus we need to be able to update the
lint results associated with a diff. This is similar to
updateunitresults, but "create" is more accurate than "update" since
we never need to change existing lint results.

getdiffproperty is used by the client to ensure it isn't creating any
duplicates lint results. It's the symmetric operation to…