Moved grain_growth_tests from combined to phase_field for #3908
Added gold files for simulations with mesh adaptivity for #3908
Merge pull request #3917 from tonkmr/MoveTests_3908

Moved grain_growth_tests from combined to phase_field for #3908
Try a longer timeout for new PBP test
refs #3024
Merge commit '4f0cf976296a15c9971dacab79d376d0ac66501a'