Add "parameter_defaults" to the environment

This give the user a way to set defaults recursively down nested stacks
without having to create the parameter in every template (it's ignored
if the template does not have the parameter).

blueprint env-nested-usability
Change-Id: Ie6b4481417204a527d322fd532c341b9acbce473
Move test_size_updates_work() to functional tests

Part of blueprint decouple-nested
Change-Id: I70e73af83e3b5a4e99c8dfdff9ad1ed4762a03af
Move test_create_config_prop_validation to functional

Part of blueprint decouple-nested
Change-Id: I3de435c2bc551fdc8ba00f069975d68d239666f1
Move test_update_group_replace() to functional tests

Part of blueprint decouple-nested
Change-Id: I7a96f5ede436e1aecac5447fef9d8ee6c5fb13a8
Updated from global requirements

Change-Id: I2627214cf7c9ebfffde9e715a69ef302b019d1c3
Merge "Updated from global requirements"
Merge "Add "parameter_defaults" to the environment"
Merge "Move test_size_updates_work() to functional tests"
Merge "Move test_create_config_prop_validation to functional"
Merge "Move test_update_group_replace() to functional tests"