Create file automatically, change tag name roles like postgis/postgis docker image

[smellman]

Changes proposed in this pull request:

• it makes easy to maintenance docker files.
  • use new postgis/postgis images but remove init script.
  • easy to generate all Dockerfile.
  • tag name to be simple: what version supports for postgresql and postgis.

@pgRouting/admins

[cayetanobv]

Great work @smellman . I think our life will be easier after this PR.