Wrapping the entire GeLoPlugin in an anonymous function to provide a safe scope to add helpers functions.
Refactoring an introducing helpers methods for making arg expectations.
Fixing bad variable name reference.
Updating GeLoCordovaPlugin to return a variable rather than a giant data structure. 

Readability matters.
Adding optional failureCallback to GeLoCordovaPlugin.on(...) function.
Re-organizing the GeLoCordovaPlugin.js to use exports so JSDoc properly documents functions via CommonJS format.

Reference: http://usejsdoc.org/howto-commonjs-modules.html
Renaming GeLoCordovaPlugin.Constants to GeLoCordovaPlugin.Events to better describe what they signify.