Making OGC TB-14 Twitcher code available

[tomLandry]

As discussed today, CRIM's version of Twitcher has heavily increased capabilities and roles compared to a Proxy. This issue is to recapitulate the major changes and establish how to reintegrate the desired changes into the Birdhouse upstream.

At the same time, there is a demand from ESA and NRCan to see this code open sourced.

[cehbrecht]

I have collected issues for the birdhouse/twitcher clean up. We need to find a way to bring our "twitcher ogc/middleware" efforts together. We might also like to have a new combined "twitcher", maybe based on flask. Currently I try to get the "birdhouse/twitcher" ready for the Copernicus requirements.

[tomLandry]

Excellent. David Byrns and Francis worked a bit on the design. We will most probably split the TEP part (Execution Management System / Application Deployment & Execution System) from the OGC work, into a new component. I'm sending you some diagrams. That will make it much easier to do a PR on Twitcher and integrate other improvements and corrections.

[dbyrns]

Since the rest interface originally planned has evolved into a full fledged EMS (OGC's Execution Management Service), we changed our mind about pushing that into twitcher.
Our new plan, as shown in the diagrams, is to move the rest interface (including dynamic apps deployment, jobs monitoring and outputs caching) into a new "bird" and strip back twitcher as a proxy but keeping our AuthN/AuthZ interface so that adapters like Magpie can be plugged by configuration.

[fmigneault]

resolved according to #21 (comment) via https://github.com/crim-ca/weaver