Add setResponsiveImages() and getResposiveImages()
Fix image dimensions for relative images. Add basic relative image test cases.
Remove un-needed flag
Update docblock for setResponsiveImages()
Improve the branches section of the readme file
Add . to acceptable class characters (see #97)
Merge image enhancements. (See #100 and #101)
Update changelog
Add relative test image for tests
Merge docblock updates from gocom/textile - thanks Jukka
Fix some minor code spacing issues
Change responsive_images to dimensionless_images
Update test case for dimensionless images
Bump version number to v.2.5.1