* helper/keysutil: Add a policy encrypted path storage
* Add vendored deps
* Fix spelling and paths that start with a /
* Add a key version template to change configure the ciphertext prefix
* Use big.Int for base58 instead of external lib
* Update go requirment to 1.10
* Add a version prefix cache
* Move logic to helper function
* Cache the template parts
* Add a storage prefix to policy
* Add an error if the policy passed in is nil
* Pull in the go1.10 version of the math/big package until we can update
* encrypt/decrypt/sign/verify RSA
* update path-help and doc
* Fix the bug which was breaking convergent encryption
* support both 2048 and 4096
* update doc to contain both 2048 and 4096
* Add test for encrypt, decrypt and rotate on RSA keys
* Support exporting RSA keys
* Add sign and verify test steps
* Remove 'RSA' from PEM header
* use the default salt length
* Add 'RSA' to PEM header since openssl is expecting that
* export rsa keys as signing-key as well
* Comment the reasoning behind the PEM headers
* remove comment
* update comment
* Parameterize hashing for RSA signing and verification
* Added test steps to check hash algo choice for RSA sign/verify
* fix test by using 'prehashed'
