use printf instead of println
state explicitly that the README must be named gopack.config
Allow to set a custom working directory.

This is at least useful for testing, but it can be useful to preserve dependencies for deployment setups that destroy the current directory.
I'm not totally sold in the variable name, I only used that because it similar to Bundler's BUNDLER_APP_CONFIG.
Remove github restriction.

I know, I know ...
Add Mercurial support.

Fixes #6
Fix command type.
Do not print where he package is pointing when we don't modify the dependency.
Merge pull request #15 from kevinburke/master

state explicitly that the README must be named gopack.config
Merge pull request #13 from technoweenie/printf

use printf instead of println
Merge pull request #18 from calavera/mercurial

Add support for Mercurial
Merge pull request #20 from calavera/ignore_empty_checkout_specs

Do not print where the package is pointing when we don't modify the dependency.
Merge branch 'master' into dependency_graph

* master:
  Do not print where he package is pointing when we don't modify the dependency.
  Fix command type.
  Add Mercurial support.
  Remove github restriction.
  Allow to set a custom working directory.
  state explicitly that the README must be named gopack.config
  use printf instead of println
Download transitive dependencies.

Organize the code a little bit to clear my mind.