Additional tests for bit length for secrets and orders

Secrets can have optional bit length and, if present, the bit length
must be an integer >= 1.

Orders must have a bit length in their secret, and that bit length is
validated to be an integer 8*n where n = 1, 2, 3 . . .

Change-Id: I68d70f80580dd7705d51f56481c857650509cc55
Merge "Additional tests for bit length for secrets and orders"