Crypto-NG: update random number generators

C++11 brings with it a set of reasonable quality random number
generators and tools to retrieve values for various ranges and types.

Use those C++11 STL <random> features to replace the use of the
varyingly broken, weak or non-standard functions: rand(), random(),
lrand48(), and drand48().

In the process we gain much faster and higher 'quality' randomness in
the auth nonces and event queue scheduling. And more "even" spread for
the ACL random feature.