Fixed comment
Move Rebasing section from README.md to CONTRIBUTING.md
Merge pull request #6403 from robschmuecker/readme-fix-1

Move Rebasing section from README.md to CONTRIBUTING.md
Updated devDependencies versions
Listview: Apply styles to immediate children of the listview only to keep styling of nested lists simple. Fixes #6397.
Collapsibles: No margin top/bottom for non-inset collapsibles (like it used to be). Fixes #6366.
Collapsible and collapsible set: Correctly toggle the ui-corner-all class in response to value changes of the inset and corners options.
Integration tests: Collapsible and collapsible set: Make sure options "corners" and "inset" play nice with each other in establishing whether the class ui-corner-all is to be turned on.
Collapsible: Toggle class ui-collapsible-inset according to the value of the "inset" option.
Integration tests: Collapsible: Make sure class ui-collapsible-inset is toggled in accordance with the value of the option "inset".
Theme: Renamed nodisc and alt icon classes to resolve conflicts. Fixes #6407.
Updated nodisc and alt classes on test page in demos.
Theme: Tweaked icon disc background color for alt icons, and the fallback hex color.
Correction in the comments for the ThemeRoller
Removed background image unsets that were only needed with the old default theme.
Theme: Added classic theme. Fixes #6244.
Demos: Added classic theme demo page. Updated default theme demo page.
Icons: checkbox-on icon background-image should override gradient background-image if this is added to the active style.
Theme: changed the name of the alt icon class in the classic theme icon CSS.
fixedToolbar: Added the new flipswitch to the tap toggle blacklist. Fixes #6414.