OutputInterface for enabling Marker/Indicator output control

- Creates an OutputInterface for general handling of 'outputs' parameter
- Adds control over Marker and Indicator output via 'outputs' parameter
- Changes Postprocessors and Materials to utilize the new OutputInterface

(closes #3702)
Because this set will be passed to the OutputInterface:buildInterfaceHideVariableList, which needs to be generic and work with PostprocessorName, VariableName, and AuxVariableName.