Add web subpackage to implement a web-kadi Django app

This does the very minimum to make Mica report pages available within web-kadi by wrapping the URL in an `<iframe>`.

It should also serve as a template for making dynamic Mica report pages, and also showing the minimum file infrastructure necessary to create a new web-kadi app for plugging in.  See also the corresponding commit https://github.com/sot/kadi/commit/87d71d9e4d481edd15dd9e1d422add49a7d82d39 for kadi.

@jeanconn - if you feel like hacking on this then leave this PR open and you can do so.  Otherwise it can be merged, probably with a version update to go along with it.

cc: @matthewdahmer