BUG-633: allow bootstrap customization

Downstream projects may need to customize Bootstrap/ServerBootstrap
instances before they are used. Create two protected methods which
can be overridden to gain access to the instances before they are used.

Change-Id: Ibb45c7b99847cbe2fe8b90e8d1bf125c66a18e0d
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-633: allow bootstrap customization"