closes#517
add index test for Application
add app.toJSON test
add test for app.inspect()
add tests for app.use()
add tests for app.onerror()
add tests for app.respond()
add tests for app.context()
add tests for app.request()
add tests for app.response
refactor for non-existence of test/app...js
no need for *.js
use helpers/ dir for non-tests
On the 3rd of February, the planned roll out on Travis was reverted
and is now rescheduled for a later date. This commit re-enables io.js
support on Travis due the original one being reverted.
