Better exceptions handling during pipeline deployment

[mpangrazzi]

This fixes #47.

I've added the bare minimum to handle any unhandled exceptions during pipeline deployment (now it returns a HTTP 500 with error details).

I've also added tests for pipeline registry, which was uncovered.

Of course, this is the bare minimum to avoid to throw and broke during pipeline deployment. I plan to add further minor improvements such as:

• use APIRouter to better organize route handlers
• extend better error handling on other routes
• type fixes

[anakin87]

Looks good.

I would suggest prioritizing the work on the CI so that we can run tests on PRs.

[mpangrazzi]

@anakin87 Thanks! Yeah, wanted to nailed this before, next step will be CI.