Add Timer class

The class provides for a timer, callback invocation on timer expiry, and
timer control/cleanup. This will be used in subsequent commits.

Change-Id: Ic8f43264a47903732b590a360ef0d8af765d5a20
Signed-off-by: Nagaraju Goruganti <ngorugan@in.ibm.com>
diff --git a/Makefile.am b/Makefile.am
index 06b7331..dbd84f9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -14,7 +14,8 @@
 
 phosphor_chassis_state_manager_SOURCES = \
 	chassis_state_manager.cpp \
-	chassis_state_manager_main.cpp
+	chassis_state_manager_main.cpp \
+	timer.cpp
 
 phosphor_bmc_state_manager_SOURCES = \
 	bmc_state_manager.cpp \