[WIP][POC] Travis-CI like line numbering and folding

[cdaguerre]

Please refer #1610.

[cdaguerre]

The build fails because I'm using my own drone instance and secrets, but I'd fix this if you have interest in this PR.

[tboerger]

You should write SASS instead of CSS and integrate it into the single generated CSS.

[bradrydzewski]

wondering if you confirmed ansi_up is able to stream output? the reason I ask is because to properly display terminal output spanning multiple lines some state needs to be maintained, since the begenning and end of an ansi termination sequence may not appear in the same chunk

[bradrydzewski]

We've moved the user interface code to a separate project. It is also now a simple-page application instead of server-side rendered + jquery. If you are interested in re-working / re-submitting to the official ui repository we can get it merged. https://github.com/drone/drone-ui