[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: 
If `_get_template_line()` is a `@api.multi` (it should be), you can do:
```
line = self._current_template_id._get_template_line(line_number)
```