Add a brief document on how to run tests

There was no guidance in the repository about the steps required to run tests,
and those are not completely obvious.  We should improve the tests themselves
to work better, but for now we can get good millage out of documenting
everything at a lower cost.

This closes #370.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Support multiple razor install types in acceptance suite

In order to transition smoothly from git to packaged versions of Razor, there
needs to be a period when we support both, so that we don't leave users high
and dry with a broken system.  Even an alpha product like this should care
about user experience at this level.

This enhances the acceptance test installer for Razor to support "package"
install mode, if we ask for `internal-packages` install mode.  The default
remains git, and we can explicitly request that also.

It also configured, in `internal-packages` mode, the internal apt package
repository that contains the artifacts of the last successful internal
package build.

Neither of those is expected to be useful from outside the walls of
Puppet Labs, but the general infrastructure will: when we establish public
package repositories, we will be able to integrate a test mode that uses
those, and ensure that we continue to pass acceptance tests with our packaged
product in the face of external change.

This is part of #307, but not sufficient to complete it.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Install the "spec" acceptance test suite to test servers

When we are running our acceptance test suite using packages, we end up
without the "spec" directory - which contains acceptance tests - installed.

That is sensible and correct, but means we need to transfer that from the git
checkout manually in order to actually test the product.

This closes #307.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>