Fixed GUI typos, wrong links, added sync functionality

- Fixed typos (Virutal -> Virtual) and some pages referencing 'setttings' instead of 'settings'
- Modified the XMLRPC Sync configuration screen, based on Squid3's screen.
- Added XMLRPC synchronization code (auto/manual, based both on "carpsettings" and "hasync" structures,
  and confirmed successful replication (no luck yet with pushing a XMLRPC reload via pfsense.exec_php)

Fix typos, added new screen for VirtualHosts backend

- Fixed typos and text in the VirtualHost config screen
- Re-indented code with only TABs in apache_virtualhost.xml
- Fixed typo within code : bowser -> browser
- Added custom field to its own screen (still need to link it), for SSLRequire & Location specific stuff
- Added custom Location settings to virtualhosts.conf generation