Update RandomizeSynapses to generate random values between -0.5 - 0.5

[danhardman]

Fixes issue #4

[NOX73]

Hi thanks for the PR.
Seed should be done in the client library. So, you should call seed for all your application before using it.

[danhardman]

That's fair but it should be clear that it should be done.

What about the multiplying the weight value by 2?

[NOX73]

@danhardman ok, let's remove multyplying
but actually, I'm not sure about that. There are a lot of recommendations about weight randomization.