Fixes for test runner

The runner's Syntax step compiled all .ts files instead of the .d.ts files. This RegExp fix cuts about 300 compiles and another 2 minutes (oops :grin:)

I also added a magic hack so when you use a branch ending on `/full` then travis will run the full test suite instead of the git changes. https://travis-ci.org/Bartvds/DefinitelyTyped/builds/20327360 with the other fix so done in 4 minutes (hah).

And also fixed a small flow flaw in the async code.