Allow running e.g. `production open`

`open` is a private method from somewhere up the inheritance chain, so
Environment tries to call it and crashes. To avoid this, we redefine the `open`
method.
Remove keyword args to support Ruby 1.9

The current implementation only uses keyword args at one point, so Ruby
2.0 is not really needed.

Also, a lot of projects still uses Ruby 1.9, so the loaded ruby will be
the 1.9 (to run tests, app etc).

So I think that is a good idea to support the 1.9 series.
Bump to 0.2.0

Changes:

* Ruby 1.9 support (previously was 2.0+).
* Allow running e.g. `production open`.
Pass in first argument when restoring into staging

* development.rb uses `first`.
* Update staging.rb for consistency.
Update console command

Fixes:

    Running `console` attached to terminal... up, run.6558
    bash: console: command not found
Bump to 0.2.1
Add binstubs, bin/setup, CONTRIBUTING.md

Improve developer experience of getting involved.