Adds capabilities support

Adds:
* Launchers & configs
* turtlebot_capabilties (moved in from https://github.com/osrf/turtlebot2_capabilities)
* rosinstaller for capabilities

To test:
* Install and compile all required sources using turtlebot/turtlebot_capabilities.rosinstall
* roslaunch turtlebot_bringup app_manager_with_capabilities.launch --screen
* rqt_capabilities
* start mobile base capability (right click on capability-> start)
* roslaunch kobuki_keyop keyop.launch