SymmetricAlgorithm.FeedbackSize must be a multiple of 8 (bits)
Remove NotWorking from some tests (that works now)
Revert "Fix CFB mode for Rijndael when data is not a multiple of block size"

This reverts commit e094d3dc0cf186f1de32d5340d847dc18aeca0e2.
Fix CFB for AesCryptoServiceProvider (only CFB8 worked, 16-64 did not) and move the different CFB implementation to Rijndael's transform (since it's the only implementation 'working' this way.
Aes.Create returns, by default, an instance of AesCryptoServiceProvider, not AesManaged (more important now than before wrt CFB support)
Fix several, but not all, cases where CFB does not work with Rijndael and AES. ref: bug #9247
Add several tests to cover CFB mode. Some are currently disabled (CFB >8 or PaddingMode != None/Zeros) for RijndaelManaged