fix for doc failure
Merge pull request #1567 from Kenneth-T-Moore/doc

fix for doc failure
fix to prevent vartrees from being checked for derivative methods
Merge pull request #1568 from naylor-b/ning_bug

fix to prevent vartrees from being checked for derivative methods
test_constat_inputs uses ConnectableMetaModel
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into feature-instance