Hypothesis-ros

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- fix invalid classifier for License

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- add strategies for
- CompressedImage.msg
- DisparityImage.msg
- Image.msg
- Imu.msg
- PoseWithCovariance.msg
- RegionOfInterest.msg
- TFMessage.msg
- TransformStamped.msg
- fix field frame_id in strategy Header.msg
- add validation in message field strategies
- refactor dublication of parameter strategies
- add missing tests for geometry_msgs
- add and cleanup tox environments
- change license to Apache 2
- fix docstrings
- improve docs

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Initial quick and dirty implementation of hypothesis strategies
for ROS msg field types, ROS parameter types and ROS msgs.

buildin msg field types:

- bool
- int8
- uint8
- int16
- uint16
- int32
- uint32
- int64
- uint64
- float32
- float64
- string
- time
- duration
- array

parameter types:

- bool
- int32
- string
- date
- list
- double

std_msgs:

- Header

geometry_msgs:

- Point
- Quaternion
- Pose
- Transform
- Vector3