Large refactoring of view code backed by adding tests for sqlalchemy model classes

Hi Claytron,
I love TodoPyramid for its idea & look and almost always refer to this example, listed on the offical pyramid tutorials page, when explaining basic pyramid principles to others. I wanted to apply many ideas to my own projects. Coming from Plone I wanted to learn sqlalchemy and deform. Thus I started exploring the implementation of almost all concepts within ToDoPyramid. This way I created a lot of Gitub issues and started hacking. Having tests for the model kept me almost safe. It is now different from the one you created, but these changes are almost transparent to a single user. I need to invest more time into sqlalchemy docs. I think now is a good moment to inform you about my work. I think the project as a whole can now communicate important concepts of pyramid application programming a bit cleaner, mostly because I refactored the big large single view class into several parts and increased readability of the source code by separating concerns. It is my first pull request on GitHub and the first thing I added to Travis CI. Please consider pulling my changes into the project or tell me your idea about publishing it to pyramid beginners.