Allow time step to increase after shrinking.

This addresses issue #3764.
small style modifications refs #3765 #3764
Add test for regrowing DT with ConstantDT refs #3765 #3764
Pruning submodule directories
closes #3853
Merge pull request #3855 from friedmud/constantDtRegrow_3764

Constant dt regrow
Merge commit 'b44aaa74e83ecfd9d6e772d94b8d35064ae014ea'
Merge pull request #3854 from permcody/prune

Pruning submodule directories
Merge commit 'ac82d5cc95c85c95e1fd6f876f6bebdd2c864925'