Activate ROS Support
Add ros support
Update TaskContext to handle alternative TaskContext types, e.g. such as Syskit::ROS::Node
ros: inject ROS specific part into Syskit::RobyApp::Configuration configuration
ros: cleanup Syskit::ROS::Node
ros: raise if project shall be loaded that does not contain any launchers
ros: require ros roby_app/plugin
ros: require :on option with use_roslauncher
ros: cleanup Syskit::ROS::Node

Nodes will directly emit :start and :stop for corresponding events and
handling of state changes is disabled by overwriting Syskit::TaskContext#update_orogen_state
ros: add include of BGL::Vertex for Orocos::ROS::Node to support RelationSpace
ros: add extension loading to ros projects
ros: load dependencies for existing ros projects
ros: require :on option when loading ros launchers
ros: adapt to fixed method names of ROS process_manager
ros: don't check all, but only available ros project in use_roslaunchers_from
Reduce calls to super in new_submodel
implement marshalling of typelib values through the droby marshalling mechanisms

This finally fixes the (many) problems we have because we cannot put typelib
values as e.g. argument or default values in actions
don't load blueprints and profiles in testing mode
app: directly feed Orocos::Spec objects instead of names to orocos.rb
app: load_dir loads all task contexts, load lazily each config file instead