Log Message:
Update ruby-pdf-reader to 1.2.0.

v1.2.0 (28th AUgust 2012)
- Feature: correctly extract text using surrogate pairs and ligatures
  (thanks Nathaniel Madura)
- Speed optimisation: cache tokenised Form XObjects to avoid re-parsing them
- Feature: support opening documents with some junk bytes prepended to file
  (thanks Paul Gallagher)
  - Acrobat does this, so it seemed reasonable to add support