refactor wmstats

Patch include following changes
https://github.com/dmwm/WMCore/issues/4530 Request Alert (initial version)
https://github.com/dmwm/WMCore/issues/4524
https://github.com/dmwm/WMCore/issues/4520
https://github.com/dmwm/WMCore/issues/4519

Also adding agent view,  adding back search option for job view