CE-2335: improve deployment error messaging
Uses the description from the server response if available, to better communicate what went wrong to the user. It now looks like this:
Steps to reproduce:
- Set the proxy to demo
- Go to http://localhost:3000/iocs/15?jobs_page=0&jobs_rows=5&tab=Management
- Use the latest revision (4333292d) and one of the ccce hosts
- Click Deploy
Closes CE-2335