Parent To Nearest Bone
In the newest version 0.9 you can now choose, which method the add-on should use, to calculate the nearest bone:
1) the object's location
2) the average location of each vertex of the mesh
3) the center of the bounding box

From version 0.4 on you can find the add-on in the armature properties:

So all you have to do is ...
1) select an armature (in the outliner or in the 3D View)
2) select all your objects in the 3D View which should be parented automatically by the add-on and press M -> New Collection
3) select your new collection from point 2) in the add-on under "Collection"
4) Press "Assign objects"
Now your armature is ready to work!
With "Check armature (colorize)" the objects and the parented bones will be colorized in the same color so that you can easily find errors in your rig.
You can reset these colors by pressing "reset colors".
Note: Colorizing in the mode "parent to armature deform with automatic weights" makes no sense so the colors will be automatic resetted in this case.