log probas -> probas; add debug info to analysis

- convert log probabilities to regular probabilities throughout the code
- add debug information to the analysis model such as the length of each window, the start date and end date, and the probabilities before a ratio is computed (raw_ratios)
- remove learn_vocabulary method from classifier as it is unecessary now that we pass in the vocab to the initializer
- fix bug in classifier where it would never initialize the tfidfvectorizer with the vocab because the if statement failed