Created OutputInterface for building generic methods for using 'outputs' in an object
(refs #3702)
Added test for OutputInterface use with Indicators
(refs #3702)
Added OutputInterface to Markers
(refs #3702)
Added test for OutputInterface use with Markers
(closes #3702)
Postprocessors now rely on OutputInterface
(refs #3702)
Material and the auto output of materials relies on OutputInterface
(refs #3702)
Made marker calculations more robust
(refs #3702)
Merge pull request #3804 from aeslaughter/indicator-output-3702

OutputInterface for enabling Marker/Indicator output control
Merge commit 'c974e33321ed327ddc11ef50d3466c7abb4ef264'