issue #23 使用logback作为单元测试的log工具，并配置默认的log

weixin-java-common/src/test/resources/logback-test.xml

@@ -0,0 +1,16 @@
+<configuration>
+
+  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+    <!-- encoders are assigned the type
+         ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
+    <encoder>
+      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+    </encoder>
+  </appender>
+
+  <root level="info">
+    <appender-ref ref="STDOUT" />
+  </root>
+
+  <logger name="me.chanjar.weixin.common" level="debug" />
+</configuration>