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

internal/ceres/problem_impl.cc

diff --git a/internal/ceres/problem_impl.cc b/internal/ceres/problem_impl.cc
index 1fb9e39..21d1144 100644
--- a/internal/ceres/problem_impl.cc
+++ b/internal/ceres/problem_impl.cc
@@ -651,7 +651,12 @@
   program.ParameterBlocksToStateVector(parameters.data());
 
   double tmp_cost = 0;
-  bool status = evaluator->Evaluate(parameters.data(),
+
+  Evaluator::EvaluateOptions evaluator_evaluate_options;
+  evaluator_evaluate_options.apply_loss_function =
+      evaluate_options.apply_loss_function;
+  bool status = evaluator->Evaluate(evaluator_evaluate_options,
+                                    parameters.data(),
                                     &tmp_cost,
                                     residuals != NULL ? &(*residuals)[0] : NULL,
                                     gradient != NULL ? &(*gradient)[0] : NULL,