Revert "Update Content-Security-Policy"

This reverts commit 99ad5995089bace233dac20de28ef021591d89c1.

Reason for revert: 
This causes a major regression on the web console.  Login page fails to load in chrome, with a content-security-policy error.  Reverting to regain stability, then we can reopen with a new patchset.

Change-Id: If75b6614ad4cd9732725893040a85589e0d1bb9a
diff --git a/include/security_headers_middleware.hpp b/include/security_headers_middleware.hpp
index 04fc913..561fd81 100644
--- a/include/security_headers_middleware.hpp
+++ b/include/security_headers_middleware.hpp
@@ -18,9 +18,8 @@
 static const char* xssKey = "X-XSS-Protection";
 static const char* xssValue = "1; mode=block";
 
-static const char* contentSecurityKey = "Content-Security-Policy";
-static const char* contentSecurityValue =
-    "script-src 'self'; object-src 'self'";
+static const char* contentSecurityKey = "X-Content-Security-Policy";
+static const char* contentSecurityValue = "default-src 'self'";
 
 static const char* pragmaKey = "Pragma";
 static const char* pragmaValue = "no-cache";