Add unit tests for utils and refactor Makefiles

1. Add unit tests for utils;
2. Put the common code shared by app and utest into a library, and link the
library to app and utest.
This eliminates the duplicated compiled objects.
3. Update .gitignore

Change-Id: I05ee93c2b23748a1e038eeec3534d49b94911366
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/.gitignore b/.gitignore
index 6c72e31..02849ca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,17 +36,21 @@
 /texinfo.tex
 
 # Repo Specific Items
-/*.o
+*.o
+*.la
+*.lo
+*.log
 /config.h
 /config.h.in~
-/config.log
 /config.status
 Makefile
 .deps
 *-libtool
-/org/open_power/OCC/PassThrough/
+.libs
+/occ_sensor.hpp
+/org/open_power/OCC/Device/
 /openpower-occ-control
+
+# UT related items
 /test/utest
-/test/utest-utest.o
-/test/*.log
 /test/*.trs