Added novice reference page on recognising shell, Python and editors within a shell window and how to exit from these
Improve "Recognising prompts" section

- Add images
- "How to exit" right after the images.
Fix English at Prompt reference

Thanks to @mikej888.
Add lines to mailmap

Related with #576.
Fix make-book.py when handle images

Add support for Markdown extension for images.
Merge pull request #582 from r-gaia-cs/fix-book-images

Fix make-book.py when handle images
Merge pull request #553 from r-gaia-cs/recognising-shell

Improve for recognising shell
Fix mailmap for Molly Gibsons

Thanks @wking for the tip at
https://github.com/swcarpentry/bc/issues/576#issuecomment-47445298.
Add dbarneche into mailmap
Add dtrap into mailmap
Add Brenna to mailmap
Add AnneTheAgile to mailmap
Merge pull request #577 from r-gaia-cs/mailmap

Add lines to mailmap