added typing of mozilla localForage library
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.
added tests
Merge pull request #1715 from panopticoncentral/master

Fixes for jake definitions
Merge pull request #1661 from 3x14159265/localForage

added typing of mozilla localForage library
fixed bluebird (dynamic version) mistake in test name

added 'preliminary typings' note to definitions
Merge pull request #1721 from Bartvds/def/bluebirdtest

fixed bluebird test name
Fixed gruntjs done() callback signature
Merge pull request #1722 from Bartvds/def/gruntjs

Fixed gruntjs done() callback signature