Check if encoded user credential may get truncated

In some deployments, user passwords are generated by other
authentication infrastructures where the length of the Base64 encoded
credentials is longer than the DB limit.

This patch checks if the encoded credential might be truncated when
it is generated and fail early during stack creation, or else it will
cause troubles later on when operating the stack.

Change-Id: I901b9e39dd0d394991520fea1f527e250c2c9680
Partial-Bug: 1386213
Small re-factoring in template_resource

Change-Id: Id416595c531db8510d9fd88d1573372f3c4934eb
Updated from global requirements

Change-Id: Ifce77584f9f29418f3b3ca47ca6fa001ded904dc
Move basic instance group functional tests

Part of blueprint decouple-nested
Change-Id: I6cb85c506a56d2fc2b8a22d1a207cfc67ee85f1e
Fixed typo in remote stack resource

This patch fixes a typo in error message in RemoteStack code.

Change-Id: I9389664743c55385c78dfc3ba43afc14e6ae8c57
Support tox test case single run

For example "tox -epy27 -- heat.tests.test_hot.StackParametersTest" will
run correctly with this patch. Otherwise the same command line still run all.

Change-Id: Ib108a6f5c319c3060475a2daa47e8e35441a840e
Merge "Fixed typo in remote stack resource"
Merge "Check if encoded user credential may get truncated"
Merge "Updated from global requirements"
Merge "Small re-factoring in template_resource"
Merge "Support tox test case single run"
Merge "Move basic instance group functional tests"