Merge class ROSScitosBase into ScitosBase

And uncouple ScitosBase and SchunkServer loops from main().
Move arm related classes from main file into new file SchunkServer.h

Classes ScitosServer and TrajectoryExecutor
Rename schunk arm topic with use of namespace, separating namespaces for SchunkServer and ScitosBase

Renamed these topics within three repositories:
* /schunk/target_vc/joint_states -> /schunk/move_all_velocity
* /schunk/target_pc/joint_states -> /schunk/move_all_position
* /schunk/position/joint_states -> /joint_states
* /schunk/position/pre_mimic/joint_states -> /schunk/pre_mimic_joint_states
* /schunk/trajectory/command -> /schunk/trajectory_command
* /schunk/trajectory/state -> /schunk/trajectory_state
Split up PowerCube class into dedicated classes

Converted PowerCube class into protocol and hardware specific classes with an interface in abstract class RobotArm

+ add robot_arm_class parameter to choose which implementing class to use
- remove disable_arm parameter
* main classes now completeley in radian
Rename schunk related topics within three repositories

Renamed topics to underscore, replacing 'target' with 'set'.
Changed type of dummy messages from type Bool to Empty.
Removed unused instance wide data members and accessors

Implemented retry loop for robot pre-initialization
Refined sonar callback
Rearrange methods between ScitosBase header and class file
Move messages into separate package metralabs_msgs

Rename message idAndFloat to IDAndFloat
Remove unused message movePosition
Remove unused services
Clean and add .gitignore files