Applying to be contributor

[Zhang Xiaoguang]

Hi,
    I would like to be added to the contributor role in order to taking some 
issues. It'll be great if some one can do me the favor!
    My JIRA username is `zhxiaog` by the way.
    Thank you for the excellent works you have accomplished on Calcite! Have a 
nice day!
     Xiaoguang Zhang