Add retrying downloading Jabba install script and cache it.

.travis.yml

@@ -11,7 +11,8 @@ before_install:
   # fetch full history for correct current and previous version detection
   - git fetch --unshallow
   # using jabba for custom jdk management
-  - curl -sL https://raw.githubusercontent.com/shyiko/jabba/0.11.1/install.sh | bash && . ~/.jabba/jabba.sh
+  - if [ ! -f ~/.jabba/jabba.sh ]; then curl -L -v --retry 5 -o jabba-install.sh https://raw.githubusercontent.com/shyiko/jabba/0.11.2/install.sh && bash jabba-install.sh; fi
+  - . ~/.jabba/jabba.sh
   - jabba install adopt@~1.8-0
   - jabba install adopt@~1.11-0
 
@@ -83,7 +84,7 @@ cache:
     - $HOME/.cache/coursier
     - $HOME/.ivy2/cache
     - $HOME/.sbt
-    - $HOME/.jabba/jdk
+    - $HOME/.jabba
 
 env:
   global: