Don't quote pure numbers

Don't quote numbers otherwise the [ruby underscore formatting](http://stackoverflow.com/questions/4946305/what-does-the-underscore-mean-in-literal-numbers) (e.g. 100_000) is rendered in templates (should that formatting be added in the future or a wrapper cookbook). 

I got bitten by this in a wrapper cookbook where, because the original attribute is quoted, it was rendered as text with an "_" which made the Zabbix server barf since that is not a valid number.