Fixes related to disabling state functionality

Found an issue in the sls function when disabling states.  Originally Ihad used the show_lowstate to get what would be applied to the minion, to check for disabled states.  Turns out this shows what would be applied during a high state and not from an SLS file.  Switching to using st_.state.compile_high_data inside the SLS and moving the show_lowstate call into the highstate function where it's correct.
This is clearly better, but we are running the compiler twice again in here, it looks to me that the disabled code needs to be reconfigured and moved entirely into salt/state.py, the way this currently works is very bad and is a performance issue