Add a timeout for waiting to STDIN?

[orta]

Still trying to figure out why builds like https://travis-ci.org/danger/swift/jobs/455599717 are failing, maybe it's because STDOUT isn't being read and we're blocking on waiting for that? Danger JS is definitely sending it.

[orta]

I could see this, if it takes under a few ms to compile the package.swift etc the delay on listening out for STDIN could take too long.

[orta]

danger-js should now be able to send the DSL down, will just need to add a timeout and ship it in danger/swift

[orta]

This is #108

[orta]

Actually
#97