Decrease lower bound on default intercept

Since intercepts are applied after the encoders, it's only the upper
bound that needs to be less than one to avoid high gains. The lower
bound should go to -1.

nengo_loihi/config.py

@@ -42,4 +42,4 @@ def set_defaults():
 
     """
     nengo.Ensemble.max_rates.default = nengo.dists.Uniform(100, 120)
-    nengo.Ensemble.intercepts.default = nengo.dists.Uniform(-0.5, 0.5)
+    nengo.Ensemble.intercepts.default = nengo.dists.Uniform(-1.0, 0.5)