Added a basic test for asynchronous support
Asynchronous tests are now added for it_, example_ and specify_.

Trailing underscore is being used for the asynchronous versions
temporarily until a better alternative can be found.

Asynchronous tests use an SPTExample subclass SPTAsyncExample.
Updated indenting metadata to comply with style guidelines
Woops, fixed the test so it will halt, but fail.
Initial implementation fo Async test running.

This implementation simply runs the test and waits for the callback to
be called. It allows the run loop to continue so it's not blocking
other actions, but as far as I can tell from the Specta codebase, it
will block other tests from being run.
fixed async spec test failing
failure to invoke callback within timeout causes async spec to fail
inspects given block to check if it's an async block - no longer needs the use of it_ for async specs.
before/after hooks accept async blocks
updated readme to contain info about async testing
version 0.1.7 - includes async testing