v2.1.0

• Added method in PebbleEngine.Builder class to completely disable cache
• Improved error message with malformed ternary expression
• Bug fix: NPE when calling bean method will null argument
• Bug fix: relative paths were not platform agnostic
• Bug fix: slice filter failed on integer argument
• Bug fix: Pebble didn't work on GAE due to a restricted class in the JRE
• Backwards incompatibility: Removed method on PebbleEngine.Builder to register a filter as safe and not requiring escaping.
  The filter should return an instance of SafeString instead.
• Backwards incompatibility: Functions are now escaped unless they return instance of SafeString