Use the SLF4J simple logger binding for the dev server

Production servers may want to use log4j12 or similar, but the point of
the dev server is to avoid the need for additional configuration.

Change-Id: I4bb3f37b9802b1e4d02fe9305162b43af52879c4

gitiles-dev/pom.xml

diff --git a/gitiles-dev/pom.xml b/gitiles-dev/pom.xml
index 1800ef9..9a447f7 100644
--- a/gitiles-dev/pom.xml
+++ b/gitiles-dev/pom.xml
@@ -50,6 +50,13 @@
       <artifactId>jetty-servlet</artifactId>
       <version>${jettyVersion}</version>
     </dependency>
+
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-simple</artifactId>
+      <version>${slf4jVersion}</version>
+      <scope>runtime</scope>
+    </dependency>
   </dependencies>
 
   <build>