Update documentation: review "what is KindleEar"
Update documentation: review chapter 2

chapter 2: Does this application require its own server?
Update documentation: review chapter 3

chapter 3: How to deploy my own delivery server?
Update documentation: review chapter 4 and 5.

- chapter 4: Why do I not receive the deliveries?
- chapter 5: What is full text rss?
Update documentation: review chapter 6, 7 and 8.

- chapter 6: Can full text rss be processed as summary rss? What about
  the reverse?
- chapter 7: How to deal with weekly subscriptions?
- chapter 8: Can KindleEar deliver news to my kindle more than once a
  day?
Update documentation: review chapter 9, 10, 11

- chapter 9: How to use the url filter?
- chapter 10: What can I do if the gfw of China blocked some rss?
- chapter 11: How to put cover and masthead images in other directory
  when I add a builtin books?
Update documentation: review chapter 12, 14.

- chapter 12: How to deal with the SSL error problem when I upload
  KindleEar?
- chapter 14: What can I do if I forget the password?
Update documentation: review chapter 16, 17.

- chapter 16: There are some logs like 'fetch rss failed(450)' in the
  gae backend, what's the meaning of them?
- Why I can't lookup words in the delivery books after I chosen 'Merge
  books into one'?
Update documentation: review chapter 19, 20.

- chapter 19: Can I delete/hide books in Chinese?
- chapter 20: What's the meaning of the "Separate" option for the
  built-in books?
Update documentation: review chapter 13.

- chapter 13: Why some articles have garbled characters?
Merge pull request #133 from lord63/faq_en

Need Review: try to refine the faq_en