Added callback to bootstrap function. Closes #11
Register multiple constants at once. Closes #5
Added callback to Injector object creator. Closes #11.
Two ways to bootstrap Injector app. Closes #12
New module definition complete. Started documention. Ref #10
Updated documentation for new module definition. Fixes #10
Support for multiple module directories. Fixes #2.

Also optimized to use more async bootup. FASTER!
Updated docs to reflect multiple directories.