Ticket #139 - Instead of using display:none, hide the editor/previewer by
setting the left position by -999999px.
Ticket #139 - Updated edit, preview, and load tests to check for -9999999px and
'' left property values instead of none/block display property values when
checking if an element is displayed or not.
Ticket #139 - Needed to remove 1 int from -9999999px to -999999px for, you know
who (Firefox). At -9999999px, Firefox converts the pixel value to -1e+7px
meaning it wouldn't be testable.
Merge branch 'develop' into feature/ticket-139-2

Conflicts:
	epiceditor/js/epiceditor.js
	epiceditor/js/epiceditor.min.js
	src/editor.js