Configure findbugs-slf4f

Also fix some logging nits.

pom.xml

@@ -249,6 +249,13 @@
         <configuration>
           <effort>Max</effort>
           <omitVisitors>CrossSiteScripting,DefaultEncodingDetector,FindNullDeref</omitVisitors>
+          <plugins>
+            <plugin>
+              <groupId>jp.skypencil.findbugs.slf4j</groupId>
+              <artifactId>bug-pattern</artifactId>
+              <version>1.5.0</version>
+            </plugin>
+          </plugins>
         </configuration>
       </plugin>
       <plugin>

src/main/java/org/gaul/s3proxy/AwsSignature.java

@@ -49,7 +49,7 @@ import org.slf4j.LoggerFactory;
 
 final class AwsSignature {
     private static final Logger logger = LoggerFactory.getLogger(
-            S3ProxyHandler.class);
+            AwsSignature.class);
     private static final PercentEscaper AWS_URL_PARAMETER_ESCAPER =
             new PercentEscaper("-_.~", false);
     private static final Set<String> SIGNED_SUBRESOURCES = ImmutableSet.of(

src/main/java/org/gaul/s3proxy/Main.java

@@ -232,8 +232,10 @@ public final class Main {
             private final StringBuilder builder = new StringBuilder();
 
             @Override
+            @edu.umd.cs.findbugs.annotations.SuppressFBWarnings(
+                    "SLF4J_SIGN_ONLY_FORMAT")
             public void print(final String string) {
-                logger.error(string);
+                logger.error("{}", string);
             }
 
             @Override

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -2850,7 +2850,7 @@ public class S3ProxyHandler {
             HttpServletRequest request, HttpServletResponse response,
             S3ErrorCode code, String message,
             Map<String, String> elements) throws IOException {
-        logger.debug("{} {}", code, elements);
+        logger.debug("sendSimpleErrorResponse: {} {}", code, elements);
 
         response.setStatus(code.getHttpStatusCode());