CONN-1258: UI Fixes for AdminGUI Account Management Pages

This PR includes UI fixes that are related to the AdminGUI Account Management pages, and referenced in CONN-1258 (https://connectopensource.atlassian.net/browse/CONN-1258).

SPECIAL NOTE:
This work also addresses CONN-1155 (https://connectopensource.atlassian.net/browse/CONN-1155).

CSS:
* pf-override.css -- added CSS rules for Acct Mgmt page, and other minor tweaks.
* dashboard.css -- added CSS rule for Acct Mgmt page.

XHTML:
* acctmanagePrime.xhtml -- incorporated HTML for Manage User Roles (taken from standalone page).
* SidebarPaneForBaseTemplatePrime.xhtml -- changed menu section for Acct Mgmt.