[REFACTOR] Extracted SarosConstants from Saros class

Change-Id: I767999e10f5296712a292cb394cfaa8990dc4ee8
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1956
Tested-by: Jenkins CI
Reviewed-by: Damla Durmaz <ddurmaz88@gmail.com>
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>