Update mysql dependency to pin to 5.3 cookbook
Install custom mysql configuration based on node.mysql.custom_config

Provide a hash of attributes that should be rendered to the custom
mysql configuration file.
Detect use of old bind_address attributes, and migrate vagrant default

The mysql cookbook no longer uses bind_address, so migrate these
configurations to declare the value as a custom config option.

Also, vagrant no longer defines a ['vagrant'] node attribute, add
a helper to detect if running under vagrant by checking for
existence of a vagrant user. This feels uncomfortable, and could
be improved.