Make kernel signature a part of the kernel preamble.

With this change, the kernel signature is a part of the preamble block (and therefore, used during preamble signature verification).

BUG=670
TEST=image verification tests still pass. corrected splicing test expectations (and it passes).

Review URL: http://codereview.chromium.org/2292001
diff --git a/tests/kernel_splicing_tests.c b/tests/kernel_splicing_tests.c
index 9335d93..241f109 100644
--- a/tests/kernel_splicing_tests.c
+++ b/tests/kernel_splicing_tests.c
@@ -65,12 +65,12 @@
   Memcpy(image2->kernel_data, image1->kernel_data,
          image2->kernel_len);
 
-  TEST_EQ(VerifyKernelImage(firmware_key, image2, 0),
-          VERIFY_KERNEL_SIGNATURE_FAILED,
-          "KernelImage kernel_data Splicing");
+  TEST_NEQ(VerifyKernelImage(firmware_key, image2, 0),
+           VERIFY_KERNEL_SUCCESS,
+           "KernelImage kernel_data Splicing");
   kernel_blob = GetKernelBlob(image2, &len);
-  TEST_EQ(VerifyKernel(firmware_key_blob, kernel_blob, 0),
-          VERIFY_KERNEL_SIGNATURE_FAILED,
+  TEST_NEQ(VerifyKernel(firmware_key_blob, kernel_blob, 0),
+          VERIFY_KERNEL_SUCCESS,
           "Kernel Blob kernel_data Splicing");
 }