Find python version using Ohai

Makes the recipe easier to setup
Remove requirements for setting python version
Add attributes to the readme file
Make the recipe work without the encrypted databag

The if statement only worked if the attribute was set
Add the encrypted databag attribute to the attributes file

Make it nil.  This is purely so people can see all the attributes
Turn package installation back into a loop

This was overwritten by a previous merge
Merge pull request #15 from tas50/master

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