TSocketPool changes

TSocketPool changes

Summary: 1] Added empty constructor
         2] Added function to set server list
         3] Made getServers return by ref
         4] Made list of servers be a list of pointers

         The last change is so that someone can pass in the list of servers and rely on TSocketPool to change the failure time directly on the TSocketServer object

Reviewed By: aditya

Test Plan: Ran with a test search server

Revert: OK

DiffCamp Revision: 9529

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665571 13f79535-47bb-0310-9956-ffa450edef68