Make SessionStore a proper singleton

- SessionStore class now has a proper singleton structure
- session_storage_singleton.hpp is removed
- from_json(..) function for SessionStore is changed to a specialized
template
- minor cosmetic fixes added
- Move the template class usages of Crow App over to a non-template 
parameter


Change-Id: Ic9effd5b7bac089a84c80a0caa97bd46d4984416
Signed-off-by: Borawski.Lukasz <lukasz.borawski@intel.com>
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b55b7c3..c050853 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -190,6 +190,7 @@
          src/kvm_websocket_test.cpp src/msan_test.cpp
          src/ast_video_puller_test.cpp
          src/openbmc_jtag_rest_test.cpp
+         redfish-core/ut/privileges_test.cpp
 	 ${CMAKE_BINARY_DIR}/include/bmcweb/blns.hpp) # big list of naughty
                                                       # strings
     add_custom_command (OUTPUT ${CMAKE_BINARY_DIR}/include/bmcweb/blns.hpp