Create a deployment tool

Create a deployment tool that codifies how we deploy applications in
Amazon Beanstalk. The design, commands and installation process are
described in the README in this commit.
Remove app package
Remove IntelliJ .iml file
Tidy up CLI

- Allow branch to be determined from the current repo to make
  creating and terminating branch environments easier
- Move non-command functions out of module to make it more obvious that
  this module is all about the CLI.
Add better error reporting

Return easy to understand error messages to the CLI for the types of
errors we expect to ecounter often.

For example errors related to timing (ie. trying to update an
environment before it's finished deploying) or related to trying to
create things that already exist.
Create a configuration template

Adds a command to create a configuration template that environment
variable can be injected into. The idea is that a highly privileged user
can create a configuration template and inject secrets into environment
variables. Then a less privileged user can create environments and
deploy versions referencing that configuration template without having
to see the secrets inside it.
Fix pip install URL

The branch identifier is required for this to work right now. Once this
branch has been merged it can be removed.

Also added a missing slash in the URL.
Add some basic logging

Add some logging to the console. This is minimal at the moment with the
idea that we can add more as we need it.
Add credentials info to README
Merge pull request #1 from alphagov/rob-play

Do deployments for Beanstalk