Keystone service throws error on receiving SIGHUP

This patch resolves following erorrs:
1. AttributeError: 'Server' object has no attribute 'reset'.
2. error: [Errno 9] Bad file descriptor
3. Can't dup an SSL object

When the SIGHUP signal is received by the service launcher in
common service framework, it calls the server's reset method.
As reset method is not present in Sever class of
keystone.common.environment.eventlet_server module, it raises
AttributeError: 'Server' object has no attribute 'reset'.

After adding reset method when SIGHUP signal is sent to service
parent process, it stops the service and then calls service start
method again. When it stops the service, it kills the eventlet
thread, which internally closes the wsgi server socket object.
This server socket object is now not usable again and it throws
following error, while restarting the service:

error: [Errno 9] Bad file descriptor

To resolve 'Bad file descriptor' error, creating duplicate
socket object, every time service starts.

As SSL object can not be duplicated, creating duplicate
socket object before converting a regular socket into an
SSL socket.

Closes-Bug: #1337850
Change-Id: I52caacc01a94428e4986ef68d032ad317e09b276
Merge "Keystone service throws error on receiving SIGHUP"