Test: scrolling and subsequent zoom

Added a test case to check that the page does not reset upon scrolling and subsequently zooming in Grid view.

Refs #138
Fixed: fullscreen mode had side margin and top border

In fullscreen mode, the diva-outer element was displaying a blue border and a margin on the left. This is not desired behavior in fullscreen.

Refs #137
Fixed: margin in fullscreen cutting off scrollbars

In fullscreen, there was a margin-left of settings.viewerWidthPadding being applied every time browser dimensions were adjusted (within adjustBrowserDims()). This is not desired behavior in fullscreen (and adding the style every time the window size changes serves no purpose). To solve this, within handleModeChange(), we instead set the margin defined by viewerWidthPadding if not in fullscreen, and one of 0px if entering fullscreen.

Fixes #137
Formatting: removed old comment and moved statement label