Add interface exception class

Add an exception class for interface errors.

Change-Id: I8409e345ff5dd5cf3744b1c2ef9501199bbadfee
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/Makefile.am b/Makefile.am
index b684c4a..572a994 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -14,6 +14,7 @@
 
 libmanagercommon_la_SOURCES = \
 	events.cpp \
+	errors.cpp \
 	manager.cpp
 libmanagercommon_la_LIBADD = $(SDBUSPLUS_LIBS) $(PHOSPHOR_DBUS_INTERFACES_LIBS)
 libmanagercommon_la_CFLAGS = $(SDBUSPLUS_CFLAGS) $(PHOSPHOR_DBUS_INTERACES_CFLAGS)