def read_config_file(filename)
      contents = ""
      File.open(filename, "r") { |f| contents = f.read() } if File.exists?(filename)
      contents
    end
def read_config_file(filename)
      contents = ""
      File.open(filename, "r") { |f| contents = f.read() } if File.exists?(filename)
      contents
    end
Read contents of config file

 If file doesn't exist, return empty string

 === Return
 result(String):: All lines in file