Genericize javascript release artifact creation

Now that we have tox-based javascript tooling, we can do tox-based
dist creation - which means that we can re-use the tooling for anything
that's grunt based.

Change-Id: I93e87b9c15cabeb9a173edb89927cf301ac24c08
Add a new node type for precise with saucy kernel

One of the types of failures in the top gate bug is due to a kernel
crash in network namespace code.  This patch installs a newer kernel on
the devstack nodes.  It installs the backported kernel and its headers
that are made available for hardware enablement purposes.  This gets
from a 3.2.0 kernel to a 3.11.0 kernel.

The patch is written as a new node prep script.  A new node type is also
defined that can be used by an experimental job.  This will allow us to
make sure everything is working before flipping the switch on using this
kernel everywhere.

The normal neutron devstack jobs are now listed in experimental.  When
run in the experimental pipeline, they should use the new node type that
uses the new kernel.

Change-Id: I9652b4183153687cc1e9a9a270ae0f78d8928620
Related-bug: #1254890
Merge "Add a new node type for precise with saucy kernel"
Merge "Genericize javascript release artifact creation"