Add certificate expiry check, events, and metrics #111

Job	Run time
build / Build	6m 22s
Docker Tests (basics)	1m 6s
E2E Tests (startup)	11m 22s
Docker Tests (bootstraptoken)	56s
E2E Tests (s3)	6m 19s
Docker Tests (cacerts)	59s
E2E Tests (btrfs)	6m 5s
Docker Tests (lazypull)	57s
E2E Tests (externalip)	8m 32s
Docker Tests (upgrade)	42s
E2E Tests (privateregistry)	9m 22s
	52m 42s

Provide feedback