Amend placeholder file extension

Fixes #534
Remove unneeded code from the MySQL example

The `boxen?` method isn't used anywhere in the file. Remove it so that there's less code for people to copy and paste and to generate less confusion as to why there's a method there that doesn't need to be there.
Merge pull request #535 from mattr-/patch-1

Remove unneeded code from the MySQL example
Add hipchat
Add 5 more things
Add jumpcut
Add info on getting it to run, todo list
Add sources for custom includes
Add sources for custom includes
Add another todo
More installation notes
Ignore .tar.gz files downloaded to vendor/puppet/cache/
Add alfred and flux