test/random.jl: segregate deterministic tests at the end

See https://github.com/JuliaLang/julia/issues/8313 for context and in particular https://github.com/JuliaLang/julia/issues/8313#issuecomment-55493151 for the rationale of this change.
In short, the first test in "test/random.jl", which needed to seed the global RNG with a deterministic value (`srand(0)`), was leaking determinism on all the tests coming after it.
Maybe something like?
```julia
srand() #Reseed the RNG with entropy from the OS
seed = rand(Uint)
#seed = 
println("Running random tests with seed\nseed = 0x",hex(seed))
srand(seed)
```