Kernel.rand nearly passes the spec

But it's not private yet.
Array#shuffle without arguments

TODO: according to specs it should accept an optional hash with :random key
pointing to a random number generator used for shuffling.
Array#rotate
remove tags
clean code
Implement most of Random.rand
Merge branch 'master' into random-rand
Fix naming of methods in W_RandomObject

method_srand is an instance method.
Don't ignore seed in Random.allocate
Use space.w_float instead of getclassfor
Whitespace cosmetics in randomobject.py
Simplify argument's coercion in Random.allocate
Untagging more Object#kind_of? specs
Merge pull request #558 from modcloth/mbh/Object#kind_of-untag

Untagging more Object#kind_of? specs
# refactor convert_types
# remove extra whitespace
Merge pull request #559 from kostya/refactor

refactor convert_types
tag new spec
Merge pull request #551 from jstepien/random-rand

Random#rand
Merge pull request #547 from kostya/rotate

Array#rotate