Fix Issue #49

spec file update for shoal agent. Now when it is being updated, the
config file /etc/shoal/shoal_agent.conf will not be overwritten. The
following message will be printed on update:

Running Transaction
  Updating   : shoal-agent-0.7.2-1.noarch
  warning: /etc/shoal/shoal_agent.conf created as /etc/shoal/shoal_agent.conf.rpmnew

This file is the default log file in the RPM and can be safely removed.