Connects to ros2/ros2#533

The storage API shall be ROS 2 agnostic and only handles the file access to read and write serialized binary code. It shall be able to describe the binary data with enough meta information to restore a complete message out of it.

Todos:

• implement abstract storage API interface: see Design abstract storage interface #8
• factory loading the storage plugin to work with: see initial version of plugin based storage api #7
• feature a SQLite3 plugin: see Implement SQLite3 storage plugin #9
• feature a ROS 1 bag plugin: see Implement ROS 1 bag storage plugin #10