Encode

[irgendwr]

Changes:

• variables in template are now encoded depending on the selected parse mode (closes #16)
• added "raw" and "brackets" renderers for special cases where you do not want variables to be escaped
• the default template and parse mode was changed, you will need to update existing notification settings!
• plugin now requires at least graylog v2.4+ but targets graylog 3.1.0
• other minor changes:
  • travis now builds using openjdk8 instead of oraclejdk8
  • minor code refactor
  • upgraded dependencies
  • updated readme