Fix Capsule docs example and remove unused import (#434)

* Fix docs error

* Remove unused import

Author: SriRangaTarun

keras_contrib/layers/capsule.py

@@ -39,7 +39,7 @@ class Capsule(Layer):
        is generally used with the 'squash' activation function
        (recommended). To use the squash activation function, do :
 
-       from keras_contrib import squash
+       from keras_contrib.activations import squash
 
        capsule = Capsule(num_capsule=10,
                          dim_capsule=10,

tests/keras_contrib/layers/test_capsule.py

@@ -4,7 +4,6 @@
 
 from keras_contrib.utils.test_utils import layer_test
 from keras import backend as K
-from keras_contrib import backend as KC
 from keras_contrib.layers import capsule
 from keras.models import Sequential