Override global jasmine spec functions
Override global jasmine spec functions

Currently, if a spec uses the global `it` function on an async test,
that test will always pass (since the jasmine version checked in Atom
does not natively support tests that return promises). This can be
confusing since the test behaviour is different between the
async-test-helpers methods and the global ones.

By overriding the global functions, we'll also be able to remove all the
imports from async-test-helpers since they won't be needed anymore.

More info: https://github.com/atom/atom/pull/18896#discussion_r260396102

atom/atom,atom/atom,brettle/atom,atom/atom,brettle/atom,PKRoma/atom,Mokolea/atom,Mokolea/atom,brettle/atom,PKRoma/atom,Mokolea/atom,PKRoma/atom