v0.4.0

• Merge pull request #4 from openstax/image-align 316b326
• take out inline property for images, and default images to be centered 06de26f
• Merge pull request #5 from openstax/extract-styles 56d1d3d
• move styles to separate dir, include w/build 5e2f943

v0.3.3...v0.4.0