Add pycrypto as a test-requirement

Adding pycrypto as a test-requirement to allow for testing the optional
KVS encryption support (ENCRYPT and HMAC validation of values).

bp: dogpile-kvs-backends
Change-Id: I2e9184dc66393cf805b18abd3822668a6f3792fa
Revert "Return a descriptive error message for controllers"

This reverts commit 6512c71a49c14e1a2f7a857a37b96883def57788.

While this fixes the problem it doesn't do it in a comprehensive way.
The right way would be to implement real validation.

The reverted patch breaks on methods marked as deprecated because the
deprecated decorator is a function that accepts *args and **kwargs.
This bypasses the check and we go back to the same TypeError from the
original bug.

Related-Bug: #1149987
Change-Id: I0efbcce9abc23bf79eb970e441e5f7644b1c8453
Merge "Add pycrypto as a test-requirement"
Merge "Revert "Return a descriptive error message for controllers""