Bump default CentOS version

[tpetchel]

In ChefDK 0.5.1, kitchen create fails against the default CentOS 6.5
configuration.

$ kitchen create
-----> Starting Kitchen (v1.4.0)
-----> Creating <default-centos-65>...
       Bringing machine 'default' up with 'virtualbox' provider...
       ==> default: Box 'centos-6.5' could not be found. Attempting to
find and install...    default: Box Provider: virtualbox    default:
Box Version: >= 0==> default: Adding box 'centos-6.5' (v0) for
provider: virtualbox    default: DownAn error occurred while
downloading the remote file. The error
       message, if any, is reproduced below. Please fix this error and
try
       again.
>>>>>> ------Exception-------
>>>>>> Class: Kitchen::ActionFailed
>>>>>> Message: Failed to complete #create action: [Expected process to
exit with [0], but received '1'
---- Begin output of vagrant up --no-provision --provider virtualbox
----
STDOUT: Bringing machine 'default' up with 'virtualbox' provider...
==> default: Box 'centos-6.5' could not be found. Attempting to find
and install...
    default: Box Provider: virtualbox
    default: Box Version: >= 0
==> default: Adding box 'centos-6.5' (v0) for provider: virtualbox
    default: Downloading: centos-6.5

STDERR: An error occurred while downloading the remote file. The error
message, if any, is reproduced below. Please fix this error and try
again.

Couldn't open file
/home/thomaspetchel/motd/.kitchen/kitchen-vagrant/kitchen-motd-default-c
entos-65/centos-6.5
---- End output of vagrant up --no-provision --provider virtualbox ----
Ran vagrant up --no-provision --provider virtualbox returned 1]
>>>>>> ----------------------
>>>>>> Please see .kitchen/logs/kitchen.log for more details
>>>>>> Also try running `kitchen diagnose --all` for configuration

It does find the correct box URL when you specify CentOS 6.6, so making
that the default.

We may want to also update Ubuntu to either 14.04 or 15.04, but the
12.04 default still functions, so I’m not touching it.

[chef-supermarket]

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Please sign the CLA here.

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[jtimberman]

This will be 7.1 with #382 😄

[danielsdeleo]

Merged as ac63468