File issues automatically

[nikomatsakis]

In my ideal world, when toolstate detects breakage in a tool, it would file an issue in the relevant tool, cc'ing all the parties involved... thoughts?

[nikomatsakis]

It might also file a rust issue, depending on whose responsibility we feel it is to fix.

I lean towards it probably being the PR author's job to fix, so that might make rust-lang/rust be the natural repository.