Generate directories even if a build.sbt file exists

[benhutchison]

For me, the most useful aspect of 'np' is the generation of src/main/scala, resources, test etc, because I use Intellij and have to do it manually otherwise. I'd like to be able to use the np command to do this, even if I have defined my build.sbt file manually. However, currently this seems disallowed:

> np
[trace] Stack trace suppressed: run last compile:np for the full output.
[error] (compile:np)
[error] existing project detected at the path /Users/ben_hutchison/swork/scala101
[error] Total time: 0 s, completed Feb 13, 2014 12:18:43 PM