Add dynamic wrapping

Dynamic wrapping allows images and add buttons to display within the width of its parent container. Dynamic wrapping overrides attributes related to a row (i.e. row-size, row-fill).

Untested for the stack variant of the card block.

This also fixes two bugs:

1. The block was rendering 10 pixels inset from the parent container.
2. When wrapping, images in the second row were indented differently from the row
above.
Merge pull request #5 from test-puddle/add-dynamic-wrapping

* Fixed formatting issues (always spaces, never tabs)
* Fixed merge conflict in CSS