This adds `new` command, which helps create a new build definition. The
`new` command is extensible via a mechanism called the template
resolver,
which evaluates the arbitrary arguments passed to the command to find
and run a template.
As a reference implementation [Giter8][g8] is provided as follows:
sbt new eed3si9n/hello.g8
This will run eed3si9n/hello.g8 using Giter8.
[g8]: http://www.foundweekends.org/giter8/
Eugene Yokota