Consistant (pseudo-)randomization in RandomBinaryProjections and RandomDiscretizedProjections

Motive: Sometimes it is desired to have stable behaviour when using random projections. The current API does not allow to set a seed for the *RandomBinaryProjections* and* RandomDiscretizedProjections*.

Solution: I added an extra parameter to the constructor of these objects called 'rand_seed' that defaults to a value that replicates the current behaviour of these classes. This parameter can be set to a seed value (see [here](http://docs.scipy.org/doc/numpy/reference/generated/numpy.random.RandomState.html) for more info) that allows for consistent behaviour. This addition is backwards compatible with the current API.

I will be more than happy to make any extra modifications if needed.