Redundant format arg in resolveFilePathRelativeToBuildFileDirectory.

Summary:
In method resolveFilePathRelativeToBuildFileDirectory, String.format
is called with 3 arguments, but the string format only expects 2.

Remove the redundant one.

https://github.com/facebook/buck/pull/61

Test Plan: Unit tests, sandcastle
diff --git a/src/com/facebook/buck/rules/BuildRuleFactoryParams.java b/src/com/facebook/buck/rules/BuildRuleFactoryParams.java
index 34d3018..341efeb 100644
--- a/src/com/facebook/buck/rules/BuildRuleFactoryParams.java
+++ b/src/com/facebook/buck/rules/BuildRuleFactoryParams.java
@@ -140,8 +140,7 @@
       path = path.substring(GENFILE_PREFIX.length());
       return String.format("%s/%s",
           BuckConstant.GEN_DIR,
-          resolvePathAgainstBuildTargetBase(path),
-          path);
+          resolvePathAgainstBuildTargetBase(path));
     } else {
       String fullPath = resolvePathAgainstBuildTargetBase(path);
       File file = filesystem.getFileForRelativePath(fullPath);