Added Darknet Tanh Test Data

Author: aryanshomray

testdata/dnn/darknet/tanh.cfg

@@ -0,0 +1,15 @@
+[net]
+batch=1
+channels=2
+height=3
+width=4
+
+# Just an identity layer to enable relative reference of shortcut layer.
+[maxpool]
+size=1
+stride=1
+
+# Shortcut is an element-wise summation of a previous layer with a referenced one.
+[shortcut]
+from=-1
+activation=tanh