Ghost keep-initial-image hack.

0. if option set:
1. chops off the blocks that match `<p><img.../></p>` and `<p><a...><img.../></a></p>`.
2. runs the regular algo.
3. re-adds the same blob.

Seems to work well for the test cases and all. I don't have much experience with regex so I'd love some feedback on its robustness.