Fixes for jake definitions

* There were a couple of definitions that were missing type decorations
that would infer "any" implicitly.
* Exec had four constructors that the actual jake object doesn't seem to
have. Exec objects are always created using createExec.
* The methods implementing node's EventEmitter didn't match the actual
EventEmitter signatures, so I updated them.
Merge pull request #1715 from panopticoncentral/master

Fixes for jake definitions