Fixed: removed 'buttons' demo

Buttons are now the default, so we do not need a separate demo for them.
Fixed: unnecessary CSS style on tools-right

The style on .diva-tools-right was causing the tools to overflow the page border by two pixels. Without the styles, the right tools are perfectly aligned with the diva-inner border.
Fixed: uneven margins when enableAutoWidth enabled

On the iPad, the right margin was smaller with enableAutoWidth enabled. This is because window.innerWidth on the iPad does not include the body margin, and so the body margin was pushing the viewer to the right. To fix this, we negatively x-offset the viewer by the body margin.

Fixes #163