Switched postfix to hiera-style configuration

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>
Add aliases file for postfix

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>
Fix syntax errors in postfix params.pp

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>
Too many comas

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>
Bracket failure

Signed-off-by: Ben Agricola <bagricola@squiz.co.uk>