Added cache in travis

- maven cache
- node_modules cache
diff --git a/.travis.yml b/.travis.yml
index dff5f3a..ef21bcf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1 +1,5 @@
 language: java
+cache:
+  directories:
+  - $HOME/.m2
+  - node_modules # NPM packages