Remove message modal window

[barryoneill]

Question/Issue Overview

Instead of using a modal dialog to display the message content, just switch out the mail list with the message view.

Multiple reasons:

• The $uibModal is an absolute pain to work with when dynamic content is involved (HTML mail contents.
• This will make it easier when we move away from angularjs, as a lot of the current code is architected around making that modal work. A purer router/template approach will make for an easier switchout.
• It doesn't work amazing on mobile.
• This isn't exactly the ideal use case for a modal, especially now there's more content in there.
• Modals suck.

[barryoneill]

The modal was removed with the great work by @tsneed290 when we switched to Vue. ( https://github.com/SpartaSystems/holdmail/issues/39 )

But going to keep this ticket open to do a few cleanup/styling tasks, and will then close it.

[barryoneill]

Will create tickets for any issues I find, let's get ready for a release.