Missing License file

[edavis10]

Can you add a License file so contributors know that this plugin is Open Source? I'd recommend GPLv2 since Redmine itself uses it. Feel free to steal my files GPL.txt and COPYRIGHT.txt:

http://github.com/edavis10/redmine_kanban

Eric Davis

[bitherder]

I've added the GPL.txt and COPYRIGHT.txt files.

Thanks for the reminder, Eric.

[edavis10]

I've change the copyright to be you, it was using my Redmine Kanban :)

http://github.com/edavis10/redmine_markdown_formatter/commit/f2408a05ea36ea336265752f8b3a66d63d00135d