Fab-support

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* Updating pelican comamnds to the parameter method of passing stage.

Note tests were failing to a non obvious cause. This was Heroku CLI needed updating to the latest version.
I manually upgraded.

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* Change the way environment variables are passed through.

In version 0.1 only the following variables were considered env variables:

'DJANGO_SECRET_KEY', 'DJANGO_ADMIN_URL', 'DJANGO_AWS_ACCESS_KEY_ID', 'DJANGO_AWS_SECRET_ACCESS_KEY',
'DJANGO_AWS_STORAGE_BUCKET_NAME', 'DJANGO_MAILGUN_API_KEY', 'DJANGO_SERVER_EMAIL', 'MAILGUN_SENDER_DOMAIN',
'DJANGO_ACCOUNT_ALLOW_REGISTRATION', 'DJANGO_SENTRY_DSN', 'XERO_CONSUMER_SECRET', 'XERO_CONSUMER_KEY'

Now there is an 'ENV' list of variables that allows any variables to be passed through and also for them to
renamed on the way from the file .env

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* First release on PyPI.