Project clj warnings

[plexus]

@eginez this is already a significantly bigger patch. I hope that's cool... If you have any feedback on this I'm happy to incorporate it. I'm also able to split this up if there are parts of it you do or don't like.

As far as functionality this

• introduces a --debug flag, so you can see the exact command being run
• deals correctly with :cljsbuild :builds being a map (instead of a vector)
• if the given build id (or "dev" if no id is given) is not found, then it falls back to taking the first build available, while giving a warning about it.

Apart from that it gives a bunch of warning messages to help the user along

• no builds configured
• target different than nodejs
• :source-paths not being a vector (I often accidentally end up with {:source-paths "src"}

I refactored things a bit. Before a lot of functions were calling the code to load and parse project.clj, now it's being parsed once and passed around.

[eginez]

looks good. Happy to take it. Would you be able to resolve the conflicts? I think taking your previous patch might have caused some of them, you should be able to rebase from master and update the PR Thanks for again for contributing

[plexus]

I expected they would conflict. Should be good to go now!