Rosdep yaml file cleaning

Cleaning enforces the following rules:
 * no trailing spaces
 * indentation is 2 spaces
 * lists of packages are in bracket [] form
 * scripts are written with the YAML | block syntax
 * items are listed in alphabetical order

A script has been provided: scripts/clean_rosdep_yaml.py
This script takes any valid YAML file and will clean it
consistently with the rules above.
Improve compatibility with debian

Most packages that are used in ubuntu also exist in debian repos.
This is an attempt at bringing some balance to improve
support for debian systems.
Merge pull request #472 from po1/clean-rosdep

Rosdep yaml file cleaning