Replace timezone-ii with rackspace_timezone

The timezone-ii cookbook isn't supported anymore, and while commits have
been made in the repo to support CentOS 7, those aren't available in the
packaged version (the one available in the Chef Supermarket).

Switch to the Rackspace fork which seems to have better support and test
coverage.
Upgrade yum cookbook, and run default recipe
Clarify SSH encrypted key error
Deduplication in release scripts
Wrapper: support overriding the re-run command

This is not used yet by the dist/install.sh script.
Move "soft" dependencies to Berksfile

Those are dependencies that aren't required to run the coobkook, but
that we'd like to package in the recipes archive (because we use them in
the wrapper's runlist directly).
Bump php dependency version
Use local patched versions of various dependencies
Check distro before installing packages

Don't attempt to install packages on a distro that is not supported!
Clear the yum metadata cache prior to adding repos
Release: 7.8.3
Merge pull request #99 from Scalr/release-7.8.3

Release 7.8.3