Pyobjects security & convention

The main focus of this pull is to limit the scope of the `exec` calls in pyobjects.

During the implementation @mgwilliams and I discussed naming convention and settled that classes should be capitalized but functions should be lower case. `Include` & `Extend` have been renamed lowercase. Also this means that `salt` is now the `SaltObject` while `__salt__` is still available for direct access, as is the case with `pillar`, `grains` & `mine` as well.