Bump the java api version for the testrunner module. No logical changes.

Summary: Allows us to compile code in IJ again.

Test Plan: Compile code in IJ
diff --git a/src/com/facebook/buck/junit/testrunner.iml b/src/com/facebook/buck/junit/testrunner.iml
index f87091a..f3fddba 100644
--- a/src/com/facebook/buck/junit/testrunner.iml
+++ b/src/com/facebook/buck/junit/testrunner.iml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_6" inherit-compiler-output="false">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_7" inherit-compiler-output="false">
     <output url="file://$MODULE_DIR$/../../../../../build/testrunner/classes" />
     <output-test url="file://$MODULE_DIR$/../../../../../build/testclasses" />
     <exclude-output />