Convert to using sdeventplus

This gets rid of the ad-hoc timer class in favor of using the timer
source built into sdeventplus.

Tested:
    Unit tests pass and everything still builds. Manually verified the
    functionality is still in tact on a zaius machine.

Change-Id: I90619f0fe5a9fdfcecd24a49de672c0c99dc95e9
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/configure.ac b/configure.ac
index 6c5ac70..cd4ae00 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,9 +19,9 @@
 LT_INIT
 
 # Check for needed modules
-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([SDBUSPLUS], [sdbusplus],, [AC_MSG_ERROR([Could not find sdbusplus...openbmc/sdbusplus package required])])
+PKG_CHECK_MODULES([SDEVENTPLUS], [sdeventplus],, [AC_MSG_ERROR([Could not find sdeventplus...openbmc/sdeventplus 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([GTEST_MAIN], [gtest_main], [],
     [