Merge pull request #18 from y-yagi/add_logger_as_dependency

Add `logger` as a dependency

Author: hsbt

syslog.gemspec

@@ -23,4 +23,6 @@ Gem::Specification.new do |spec|
   end
   spec.extensions    = ["ext/syslog/extconf.rb"]
   spec.require_paths = ["lib"]
+
+  spec.add_dependency "logger"
 end