Report connection establishment time
Report accurate op time by excluding checkout time

Fix operation time to not include the checkout time and expose it is a bean.
Jmx changes for conn establishment and op time

Jmx changes related to connection establishment time and operation
time.
Make sure bean is registered only once

A potential race can cause the bean to be registered more than
once. This commit uses the return value of putIfAbsent to short
ciruit the registration code.
Add comment explaining potential race and fix
Use time based counter instead of sample based

Use RequestCounter for connection establishment metrics
Lower down the reset value to 60 seconds