add multisite support

[bdolor]

• adding namespace
• multisite support
• checkbox options replace text input
• implementing coding standards
• introduce class variables
• sanitize input

@alexpflores - please review this Pull Request and merge if acceptable. It's a bit premature, but wanted to get the ball rolling.

[alex-418]

Looks great, love the checkboxes. Tested on my local, everything works fine, but what happens in the "Test Endpoints" section when you click one in a multisite setup?

Also, wondering if there's any value in identifying and then displaying what plugin registered the custom post type? Looking at this list, not sure where 2-3 of these are coming from. Not sure if there's an quick way of doing that.

[bdolor]

a9f268c will take care of test section on multisite. What ends up happening is that although the new route is registered for all sites in a multisite, the link is based off of the network url, which more often than not does not contain the custom post type. If this test section were to work, it could grab one of the sites on a multisite, and provide that as a test route, or it could just be removed. What do you think?

[alex-418]

I think that a quick note pointing them in the right direction on how to test their endpoints should suffice.