message: Mark client version as not a realse version.
diff: @@ -4,7 +4,7 @@ define(_CLIENT_VERSION_MAJOR, 0)
  define(_CLIENT_VERSION_MINOR, 15)
  define(_CLIENT_VERSION_REVISION, 0)
  define(_CLIENT_VERSION_BUILD, 1)
  -define(_CLIENT_VERSION_IS_RELEASE, true)
  +define(_CLIENT_VERSION_IS_RELEASE, false)
  define(_COPYRIGHT_YEAR, 2017)
  define(_COPYRIGHT_HOLDERS,[The %s developers])
  define(_COPYRIGHT_HOLDERS_SUBSTITUTION,[[Bitcoin Gold]])
  