Add API to retrieve settings

Add API to retrieve and cache settings objects of interest.

Change-Id: I8afd58b5b3e9a691e4d3fa6bfba2ba5c92cd2568
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
diff --git a/configure.ac b/configure.ac
index 7efb842..9c909ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -26,6 +26,8 @@
 PKG_CHECK_MODULES([SYSTEMD], [libsystemd >= 221], [], [AC_MSG_ERROR(["systemd required and not found"])])
 PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging],, [AC_MSG_ERROR([Could not find phosphor-logging...openbmc/phosphor-logging package required])])
 PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces],, [AC_MSG_ERROR([Could not find phosphor-dbus-interfaces...openbmc/phosphor-dbus-interfaces package required])])
+PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus],,\
+    AC_MSG_ERROR(["Requires sdbusplus package."]))
 
 AS_IF([test "x$enable_softoff" != "xno"],
     # Check for sdbusplus