Revert "Sortable: modified the contents of placeholder to a single "&nbsp;". Fixed #8135 - sortable: Horizontal sortable shifts causes elements to shift down."

This reverts commit b6e1f25ab8c038306146a6ead041dc18bfb9e8c2.
Revert "Sortable: Always set placeholder size when necessary. Fixes #8262 - jQuery UI 1.8.19 don't respect forcePlaceholderSize."

This reverts commit 4f19289c10e733a07cf60435c2e5df4ed2e23d37.
Autocomplete: Prevent the default action on escape when the menu is open. Fixes #8282 - Double escape clear IE form, continue Ticket #7643.
Draggable: Don't run stop methods for elements that have been removed.  Fixed #8269 - Removing draggable element on drop : a(this).data("draggable") is undefined.
Sortable: update placeholder when axis is x or y. Fixed #8274 - placeholder doesn't move when dragging outside of container element
Tooltip: Only check if the element is active if the event that is causing the tooltip to close is not focusout.
Grunt: Update to testswarm@0.2.1, fixes timeout handling
Grunt: Add copy:dist_units_images target to get rid of 404s when running unit tests against minified files
Datepicker range demo: Use public APIs. Fixes #8292 - Double Click on from date in Date range datepicker.
Update to QUnit 1.6.0
Don't run JSHint on TestSwarm.
Core tests: Fix double focus in IE
Tabs tests: Work around IE quirks.
Position tests: Work around IE6 bug with forced heights on small elements.
Update node-testswarm to 0.2.2
Grunt: Cleanup testswarm task, increase timeout to 20 minutes (until BrowserStack queue is increased)
Position: Apply IE6 line-height workaround to deprecated tests, too
Sortable: Moved change of helper position css. Fixed #5321 – Helper in a bottom-positioned Sortable is positioned wrong on drag start.
Dialog: Handle escape for all overlays. Fixes #8300 - Dialog: Incorrect behavior for ESCAPE with multiple modal dialogs.
Dialog: Removed trailing whitespace.