The Tool model has a handful of properties which proxy things which

are provided by the SCMTool subclass. This was used a long time ago to

make it easier to render things in templates (since trying to access the

class in the template would end up instantiating it). We haven't used

templates for this stuff in a long time, and all our code accesses these

via the scmtool_class property rather than these proxies.
This change adds a wrapper which will raise a deprecation warning if any

of these properties are accessed via the tool.

Opened a shell, enabled all warnings, and then accessed properties via

  the tool instance. Saw that I got the correct results, and that the

  deprecation warning was raised.
Ran unit tests.