Add a new Security Center Widget in the Admin Dashboard which gets data

from SecurityCheckRunner() and displays the count of errors as well

as the short error messages from each one. The widget also has a 'More'

button which goes to the Security Checklist page and a 'Reload' button

which reruns SecurityCheckRunner() and refreshes the widget data.

Added and registered the widget and confirmed it appears on dashboard
Tested by appending datetime.now() to the error_msgs returned by

SecurityCheckRunner and ensuring it updated on hitting Reload
Used the above method to also confirm refreshes on the dashboard