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
Setting $? in Kernel#`

although with stubs in place for Process::Status#stopped? and
Process::Status#exited?
Using the existing IO#pid accessor
Unstubbing and doing as JRuby does

for `Process::Status#exited?` and `Process::Status#stopped?`.
NoMethodError is kinda like NotImplementedError, right?
Integer#times without block returns Enumerator
Implement most of Random.rand
Merge pull request #550 from jstepien/integer-times-without-block

Integer#times without block returns Enumerator
remove a few specs around enumerators
Adding File::NULL
Merge pull request #553 from modcloth/mbh/file-null

Adding File::NULL
Passing more File.dirname specs
Meant for this to be the assertion
Merge branch 'master' into random-rand
Merge pull request #554 from modcloth/mbh/File.dirname-more-stuff

File.dirname trailing slash (untag specs)
Fix naming of methods in W_RandomObject

method_srand is an instance method.