[CF-165][] Preferences service: Externalize configurations
  - Using external logback file. If its not present, use the one in the classpath
Merge remote-tracking branch 'upstream/master' into cf-165-cf-322-externalize-config
Merge pull request #12 from ChandraAddala/cf-165-cf-322-externalize-config

Cf 165 cf 322 externalize config