added preliminary spi and uart test project sources for stm32 eval board from china

diff --git a/spi_on_demoboard b/spi_on_demoboard
new file mode 160000 (submodule)
index 0000000..14385ed
--- /dev/null
+++ b/spi_on_demoboard
@@ -0,0 +1 @@
+Subproject commit 14385edec309dbc058838d8ad0edfc2981208e7a