Set hyperopt seed

[LouiseABowler]

Hyperopt has the option to initialise its internal RNG via the rstate argument, which isn't set at present (rng_seed in the list of hyperparameter options is used by Lasagne). If we explicitly set rstate, can we reliably obtain the same set of hyperparameters from the optimisation process?

[LouiseABowler]

793612c adds the ability to specify the seed for hyperopt using the --hseed option when running outer.py.