Update README.md
Update Travis badge
Add Ruby 2.1.0
Add debugger gem
Convert about template
Update about template
Handle old book site's url path
Use 1.9.2 for Travis CI
Added scrollbars for overflowing lines. Fixes #354

Added scrollbars for overflowing lines of code in code snippet blocks.
Merge pull request #355 from rishabhsrao/master

Added scrollbars for overflowing lines. Fixes #354
Fix Downloads table layout.
Merge pull request #357 from jdennes/fix-downloads-table-layout

Fix Downloads table layout
recompile assets (for heroku)
Update footer links
Fix 404 links to old github url (gitscm-next)
Merge pull request #360 from xbx/bugfix-404-links-to-old-github

Fix 404 links to old github url (gitscm-next)
added git-draw to documentation/external-links
Merge pull request #358 from sensorflo/git-draw

added git-draw to documentation/external-links
Update README.md
Make the distinction between source and platform releases clearer

The current wording seems to make the difference too subtle for a casual
reader; try to clear this up by:

- naming the latest release "source" instead of "stable" release, to
  make clearer what it is that we're showing the version for.

- reword the button to "Downloads" for a platform, which makes it a noun
  for the available downloads, rather than a verb which can too easily
  be taken to mean "download this version"

This should reduce the incidence of people complaining that the version
in the front is erroneous.