Handling of pro forma (empty text) bills

Bills [C-1](https://www.buildcanada.com/bills/C-1) and [S-1](https://www.buildcanada.com/bills/S-1) have no text. They are [symbolic bills](https://en.wikipedia.org/wiki/Bills_C-1_and_S-1) and are done at the opening of a parliamentary session.

A couple of options:
1. Filter out these bills from analysis (blunt solution)
2. If a bill has no text associated with it, do not run an analysis. The summary should just state that no bill text is provided, and the vote should be "neutral". This would be a more robust solution to handle cases in which we can't get bill text for whatever reason.