Add some tests to new wrapping image
Keep image aspect ratio if only 1 dimension styled

If only one of image width or height is specified, then scale missing
dimension to maintain the aspect ratio.
Merge branch 'master' of https://github.com/brunocasado/PHPWord into 'develop'
Update CHANGELOG
Merge branch 'develop' of https://github.com/japonicus/PHPWord into develop
Update unit test and changelog