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.