Update .gitignore to ignore *.swo files

For the fellow vim user.
Test cases for ignoreDotFile

Meant to commit this earlier, but it's a basic unit test.
RenderThing test cases

Provide unit test support RenderThing.

One observation is that creating the site.Tmpl variable is a one time
event.  site.Tmpl doesn't like additional templates with the same name.
This means that updating a template while in --watch mode requires
throwing away the entire Site object and creating a new one.  Not that
this is a bad idea, but it is something I discovered while working on
these unit tests.