Require json to unbreak logging with latest fpm.
Add changelog for 0.12.0.
Bump version to 0.12.0.

Changes:

* Copy source files with no or unknown file extension to
  the source dir. (smasset)
* Set deb_user and deb_group attributes to root.
* Ensure passing the vendor attribute to fpm. (aussielunix)
* Unbreak logging with the latest fpm.