Create a self-contained 'eb' installer

This script will:

- create a unique virtualenv for the EBCLI
- create .py, .bat, .ps1 wrappers around it such that when any of
  these wrappers is invoked to execute an 'eb' command, the unique
  virtualenv is activated. After the 'eb' process is returned, the
  virtualenv is deactivated.

Author: rahulrajaram