Fix state.show_top to return the exact data as used by state.highstate

As @madduck discovered, the state.show_top function does not return accurate data. It currently returns all top data for all minions. The expected output is to return the exact data that is used for running a minion's state.highstate call.

state.show_top also breaks if both top.sls and master_tops are used. The expected result is to compile top.sls first, then merge the master_tops data.

This pull request fixes both issues.