Fix app HTML meta headers

Following the official Bootstrap template
(Not sure why but it must be important. :-þ)
Webapp: Add custom CSS

We need to customise some CSS − not everything
is in the Bootstrap template
Webapp: Add page for FDC reporting
Webapp: Fix link to GitHub account
Webapp: Add imports for Wm_metrics module

We have to manually add wm_metrics to the Python Path
Webapp: Add FDC report computation
Wrap database connection in try statement

The database connection might fail.
We want to raise an exception when that happens.
Webapp: Add error handling when FDC reporting fails

With accompanying HTML error page