Evaluate ResidualBlocks without LossFunction if needed.

1. Add the ability to evaluate the problem without loss function.
2. Remove static Evaluator::Evaluate
3. Refactor the common code from problem_test.cc and
   evaluator_test.cc into evaluator_test_utils.cc

Change-Id: I1aa841580afe91d288fbb65288b0ffdd1e43e827
diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index 5440713..703a9e7 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt
@@ -215,7 +215,11 @@
 
 IF (${BUILD_TESTING} AND ${GFLAGS})
   ADD_LIBRARY(gtest gmock_gtest_all.cc gmock_main.cc)
-  ADD_LIBRARY(test_util test_util.cc numeric_diff_test_utils.cc)
+  ADD_LIBRARY(test_util
+              evaluator_test_utils.cc
+              numeric_diff_test_utils.cc
+              test_util.cc)
+
   TARGET_LINK_LIBRARIES(gtest ${GFLAGS_LIB} ${GLOG_LIB})
 
   MACRO (CERES_TEST NAME)