Refactored existing decryption code slightly

This will make it easier to isolate the old code and only call it if no file with the new format is available.  The Get-DscEncryptedPassword function will be the branching point; it will first try to call into the new code, and then call Import-LegacyEncryptedCredentials if that fails.
Encryption updates

Code now uses the ProtectedData library for performing encryption and decryption of credentials.  Files encrypted with older versions of the module are still readable for now; the module attempts to import the old format file if the new format is not found.
Updated examples Readme
Added new Readme in the Tooling root folder

Lists external dependencies and where to find them.
Merge pull request #87 from devopsguys/EncryptionUpdates

Encryption updates