CONN-1225: Add Custom Scrollbar to AdminGUI Sidebar Nav

This PR adds a custom scrollbar to the AdminGUI sidebar nav.  This scrollbar uses the same library used by the Primefaces Showcase website.

Side Note: This PR also includes minor style adjustments to elements in the Domain Edit modal window (tab bar style, secondary form box color).

CSS:
* pf-override.css -- adjusted CSS for Domain Edit modal.
* dashboard.css -- adjusted CSS to accommodate new custom scrollbar.
* perfect-scrollbar-0.4.10.css -- CSS rules for the custom scrollbar.

JS:
* sidebar.js -- added code to activate the custom scrollbar.
* perfect-scrollbar-0.4.10.with-mousewheel.min.js -- code library for custom scrollbar.

XHTML:
* BaseTemplate.xhtml -- added links to new CSS and JS files.
* BaseTemplatePrime.xhtml -- added links to new CSS and JS files.
* SidebarForLogin.xhtml -- updated with copyright.
* SidebarPaneForBaseTemplate.xhtml -- minor reformatting.
* SidebarPaneForBaseTemplatePrime.xhtml -- minor reformatting.