Source object for rendering templates

This adds a source object for specifying and rendering template
files.  Create a source object for the given root of source files
you want to render.  It knows the root dir of the files it can
render plus the eruby/context class to render them with.

This is setup for implementing Deas' rendering API.
basic template engine with rendering api not implemented

This gets the basic template engine in place with the rendering
api not implemented for now.  This is setup for implementing the
render api at the source and hooking it up to Deas via the template
engine.

This covers the basics: setting the default logger/view locals,
creating the source object with the logger and setting up the render
API.