ICryptoProvider now allows the caller to optionally control the symmetric encryption key and IV.
Fixes failing unit test.
Adds ICryptoProvider methods: EncryptAsync DecryptAsync.
Not yet implemented anywhere.
Revised Encrypt method to take SymmetricEncryptionVariables instead of key and iv separately.
Implements the async symmetric crypto methods.
Merge branch 'asyncEncrypt'
Increments version to 0.2.1.0
Adds CancellationToken parameter to async symmetric encryption methods.
Fixes build break.
Adds SignHash, VerifyHash, and HashAsync methods to the ICryptoProvider interface.
Adds ICryptoProvider.ComputeAuthenticationCodeAsync
Adds missing CancellationToken to ComputeAuthenticationCodeAsync.