- adds a library to compute the SHA-256 hash
- updates the RSA verifier to take an argument specifying either SHA-1
or SHA-256
- updates DumpPublicKey to with new "key" version numbers for
specifying SHA-256
- adds new argument to adb auth code to maintain existing behavior
Change-Id: I5b1406cf57c2b8993f6032eda3e29139f7740839