Restores default dispatch return value

[jakereps]

Fixes #24

Tested both Main and Renderer side using a console.log() on the dispatch call.

console.log(store.dispatch({ type: 'DO_NOTHING' }));

Each call successfully resulted in the following outputs:

Renderer:

Object {type: "DO_NOTHING", source: "window 1"}

Main (electronBrowserEnhancer):

...
 { type: 'DO_NOTHING', source: 'main_process' }
...

[samiskin]

Could you make sure this also works on the Main process? (electronBrowserEnhancer)

[samiskin]

Also could you give a brief description of what you did to test this? Sorry I don't have unit tests 😞

[jakereps]

@samiskin, no problem, should be good now! Tested both the same way to make sure it was working correctly.