[8.0] Port the module 'account_move_template' to the new API

This PR contains the module ***account_move_template*** ported to the new API.
Test and installation seems to me ok.

Let's see what will be the TravisCI response and your reviews :wink: 
Beware with assignments on `self`. `self` can be a model or a recordset, which can change according to the decorator of the method. I'm not sure that you can safely assign a new attribute on `self`. It would be better to pass "computed lines" to `self.lines()` with an argument.