Document the extra_data argument to Backend.parse_answer

This has been there since forever, but didn't make it into the custom backends
guide for some reason.
Hiera 1.3: Document lookup functions in interpolation tokens

This commit also makes references to interpolation throughout the manual more
agnostic about what's being interpolated, as it may not necessarily be variables
anymore.
Remove "coming soon" space for a puppet backend example

It's not coming soon, sorry.
Hiera 1.3: you can now interpolate into hash keys
Put improved delayed_job instructions into 3.0 and 2.8

This was already added to 3.1.
Corrected wrong facter version in Release Notes, removed forgotten 3.0 info from appendix and what's new.
Merge branch 'master' of github.com:puppetlabs/puppet-docs
Add back known issues
Retroactively add the thing about puppet:/// URLs to Puppet 3.0 release notes
Added a missing comma and fixed a formatting issue on PE System Requirements.
Merge branch 'master' of github.com:puppetlabs/puppet-docs
More formatting fixes on system requirements.
Update package repo guide with x86_64 repos for redhat-alikes
Give community info pages their own sidebar
Specify sidebar in package repos page

Because I forgot how our nav snippets work.
Hiera 1.3: Release notes (for RC2)
Note that datadir must be a string

See redmine #21669.
Merge branch 'hiera_13'
Puppet 3.3.2 release notes