Added support for environment variables

Added cf-env to list environment variables, cf-add-env to add
environment variables, and cf-delete-env to delete environment
variables.
Added info about environment variables

and corrected formating of config example
Added Map/Unmap functionality

cf-map - maps uris to the application
cf-unmap - unmaps uris to the application
Added environment variables to push and update tasks

Sets environment variables on push or updates
Added details to readme file
Modified to prevent duplicate uris
Merge pull request #1 from springyboing/master

Added:

cf-env: Lists environment variables
cf-add-env: Adds environment variables to the application
cf-delete-env: Removes environment variables from the application
cf-map: Maps uris to the application
cf-unmap: Unmaps uris from the application