Fixed crashes report at https://github.com/httpswift/swifter/pull/182#issuecomment-241281054

Sources/HttpRouter.swift

@@ -100,11 +100,11 @@ public class HttpRouter {
             params[variableNode.0] = pathToken
             return findHandler(&node.nodes[variableNode.0]!, params: &params, generator: &generator)
         }
-        if let _ = node.nodes[pathToken] {
-            return findHandler(&node.nodes[pathToken]!, params: &params, generator: &generator)
+        if var node = node.nodes[pathToken] {
+            return findHandler(&node, params: &params, generator: &generator)
         }
-        if let _ = node.nodes["*"] {
-            return findHandler(&node.nodes["*"]!, params: &params, generator: &generator)
+        if var node = node.nodes["*"] {
+            return findHandler(&node, params: &params, generator: &generator)
         }
         return nil
     }