Allow the user to install this version of the plugin and the original SOAP version at the same time

[gdespirito]

As mentioned here, we should implement the REST version of the plugin as a new plugin, and not as an update.

As @leosoto commented, this will bring:

Robustness (i.e, we don't break anybody's site because he forgot to uninstall the old plugin or installed the new plugin without setting it up yet)

A transition-path (i.e, if I had a store I wouldn't completely nuke the old setup before trying the new one, so it is totally expected that people will have both plugins installed and even active at the same time before turning off the old one).

Please, consider this approach on this plugin.