small update to maintenece utils
Update exemplar sources.

- sources point to custom branch of rosdistro containing converted rules files

- use the provided testing sources and cache by running from the directory of
  the xylem source checkout:

      xylem resolve boost --prefix prefix
Merge pull request #23 from catkin/utils

Small util fixes and updated example sources

- small tweaks to code maintenace utils
- sources point to custom branch of rosdistro containing converted rules files
- use the provided testing sources and cache by running from the directory of
  the xylem source checkout:

      xylem resolve boost --prefix prefix