Move `deploy` code to zpm module

This minimizes the amount of code in the `deploy` command wrapper
function, and moves all of the logic to an API function in the `zpm`
module called `deploy_project`.

TODO: Break up the `deploy_project` into smaller chunks and write tests
for it.
Merge pull request #65 from larsbutler/refactor-test-deploy

Move `deploy` code to zpm module