Revert "Revert "Merge pull request #96 from j00k/override_browser_stylesheet_padding_in_buttons""

This reverts commit 75ae87437847c57d297c3ba7d67a9edeffd0e2ca.
Use inline-block mixin rather than display: inline-block in .rs-edit buttons. This makes it consistent with other icon buttons.
remove explicit background colour from rs-edit button
add rs-edit button to table screenshots
Merge pull request #98 from j00k/override_browser_stylesheet_padding_in_buttons

Override browser stylesheet padding in buttons