Previously, we were inconsistent on how we handled argument validation
in the CLI. Many commands used cobra.Command's Args property to
provide a validator if they took arguments, but commands which did not
rarely used cobra.NoArgs to indicate this.
This change does two things:
1. Introduce `cmdutil.ArgsFunc` which works like `cmdutil.RunFunc`, it
wraps an existing cobra type and lets us control the behavior when an
arguments validator fails.
2. Ensure every command sets the Args property with an instance of
cmdutil.ArgsFunc. The cmdutil package defines wrapers for all the
cobra validators we are using, to prevent us from having to spell out
`cmduitl.ArgsFunc(...)` everywhere.
Fixes#588
Now, instead of having a .pulumi folder next to each project, we have
a single .pulumi folder in the root of the repository. This is created
by running `pulumi init`.
When run in a git repository, `pulumi init` will place the .pulumi
file next to the .git folder, so it can be shared across all projects
in a repository. When not in a git repository, it will be created in
the current working directory.
We also start tracking information about the repository itself, in a
new `repo.json` file stored in the root of the .pulumi folder. The
information we track are "owner" and "name" which map to information
we use on pulumi.com.
When run in a git repository with a remote named origin pointing to a
GitHub project, we compute the owner and name by deconstructing
information from the remote's URL. Otherwise, we just use the current
user's username and the name of the current working directory as the
owner and name, respectively.
