Pinax notifications templates use hard-coded "http" instead of `default_http_protocol`

[fvicent]

Many templates in geonode/templates/pinax/notifications use hard-coded "http" protocol to build URLs, such as:

https://github.com/GeoNode/geonode/blob/7cac111e745430fb54ee4142410d7bb756d7d720/geonode/templates/pinax/notifications/account_approve/full.txt#L3-L5

On the other hand, some templates use the default_http_protocol context variable defined by Pinax (based on settings.PINAX_USE_SSL) instead. This should be the rule:

https://github.com/GeoNode/geonode/blob/7cac111e745430fb54ee4142410d7bb756d7d720/geonode/templates/pinax/notifications/email_body.txt#L7-L9