accounts.php: undefined variables

httpd ssl error log complaining about variables being undefined, every
time this page is visited added simple isset test to resolve the issue.
dashboard.php: function parameters

Added quotes around function parameters that were initially being
interpreted as constants, then assumed to be strings, according to the
httpd ssl error log, every time the page was visited.
functions.php: undefined variable, timezone

httpd error log complaining about continent being undefined, added
simple test/set to resolve the issue.
Updated getCurrentTimeZone() with OS detect to remove the need to
modify the file during RHEL/CentOS installation.
networkSettings.php: undefined index

httpd ssl error log complains about undefined indexes if the DNS
servers ore not both populated. Resolved with simple isset test.