[ADD] basic metadata handling;
[CHANGE] not setting node attributes to add metadata;
[CHANGE] rubocop compliance;
Merge pull request #110 from Bigpoint/bpmeta

Bpmeta
Merge remote-tracking branch 'remotes/origin/next'

* remotes/origin/next:
  [CHANGE] rubocop compliance;
  [CHANGE] not setting node attributes to add metadata;
  [ADD] basic metadata handling;
increase version number to 0.1.135