Update download instructions

Github raw (served by Fastly) does not suppot SSLv3 anymore (re:
POODLE), so update our instructions to no longer use that.

While we're at it, get curl to output more meaningful errors.
Temporarily disable Cost Analytics in deployment
Fix CherryPy wheel packaging issue
Support both Mac OS sed and GNU sed
Use pkill to kill Python processes on RHEL

Regular kill doesn't kill the entire group, which is a problem with
e.g. the Plotter where we have multiple processes.
Release: 6.2.0
Merge pull request #56 from Scalr/release-6.2.0

Release 6.2.0
Add ZMQ PECL dependency and libraries it requires
Release: 6.3.0
Merge pull request #57 from Scalr/release-6.3.0

Release 6.3.0
Fix RHEL kill command

Two fixes:

  + The ppid and pid may differ
  + If the process hasn't launched yet, don't try and kill it
Release: 6.3.1
Merge pull request #58 from Scalr/release-6.3.1

Release 6.3.1
Add PHP fatal error logging configuration
Release: 6.3.2
Merge pull request #59 from Scalr/release-6.3.2

Release 6.3.2
Externalize the ntp and iptables cookbooks

We now configure ntp and iptables through attributes and run them
through the chef-solo runlist.

We keep them in the metadata file so that berks packages them for us.
Make NTP and iptables management optional
Re-create run list everytime the installer runs

This ensures that options like --no-ntp are taken into account, and
aren't discarded based on an existing solo.json
Conditonally ask for SSH key based on git repo URL

It's not useful to ask for a private key when using a HTTP URL, and it's
very confusing. Only ask for it when it looks like it might be needed.