Ruleset shouldn't include own sniffs unless to configure them

[Eloy Lafuente]

In #71 it was detected that, lately, we have been adding moodle.* sniffs to the moodle/ruleset.xml file.

And that's not needed, unless:

• We want to change the default severity of the Sniff (or disable it).
• We want to configure some option, not default.

So this issue is just about to review moodle/ruleset.xml and remove any rule referencing to moodle sniffs, because it's not needed.

Ciao :-)