restart_command and master.cf management

Hi!
Instead of opening a feature request as we discussed by email some weeks ago, I thought it would have been more useful for both of us if I provided some code :)
So here it is:
1. restart_command parameter to let the user decide how to restart postfix upon configuration changes (in a high-traffic production environment a full restart is often undesired -- a reload is better and almost always enough); I made these additions in the 'general settings' sections of source files, because this is not something strictly related to postfix, but could be extended to other modules as well.
2. a subclass (postfix::mastercf) for master.cf config file management (I used previously submitted code as examples, i.e. postfix::aliases class).

I hope that coding style is appropriate and that my integration choices are acceptable.

One note: I've found a possible typo in documentation, that I didn't edit because I think it involves other modules too:
init.pp:
# [*template*]
#   Sets the path to the template to use as content for main configuration file
#   If defined, postfix main config file has: content => content("$template")

The name of the function should be 'template()', if I stand correct.

Well, that's all, thanks again for your modules, and please let me know if you need me to make any changes to my code.

Bye!
Fabio