Move back to the ondrej/php55 PPA for PHP 5.5

The move to PHP 5.5 as stable in ondrej surprised us a long while
ago, but not we (and WordPress core) are better prepared.

This will cause the latest stable of PHP 5.5 to install during
provisioning if the package is not yet installed. To force,
a vagrant destroy and vagrant up should be used.
Remove php-apc package installation

PHP 5.5 brings us a built in Zend Opcache and it does not appear
that APC has been deemed compatible with PHP 5.5. Either way, it's
on the way out and we should drop it.

This means that anything relying on APC for an object cache will
not work. See also -> we install memcache.
Don't copy an APC ini that doesn't exist.
And don't tell everyone we copied the APC ini...
Provide a custom opcache.ini for php-fpm

This is a copy/paste from the default opcache config provided
in php.ini during installation. The next step will be to configure
a few settings.
Enable opcache and set initial memory limit to 128

This mimics the settings that were in place for APC.

We can address the log settings with another log ticket, as it
would be interesting to have a specific log file for opcache
errors, especially because it is new.

Some of the other settings are interesting enough to leave in this
file, but should probably only be changed on a project by project
basis until we know more.
Add a custom php5-fpm.conf file

The initial file is a direct copy/paste of that provided by
default in PHP 5.5. We can make customizations from here.

This will help when figuring out where to put logs.
Clone Opcache Status during provisioning

This provides a great dashboard to view opcache statistics.
Add a dashboard link to the opcache status page
Correct the VVV repository link in VVV's dashboard
Update README with new PHP version

Adds PHP 5.5
Adds Opcache Status link
Sets VVV master to 1.2-working
Update CHANGELOG
Additional CHANGELOG updates for APC/opcache

Always with the little tweaks.
Merge pull request #295 from Varying-Vagrant-Vagrants/php55

[PR] Install and configure PHP 5.5 and other goodies during initial provisioning