sdbus client: add retries

Handle busy responses from the server with retries.

Change-Id: I8c13faddec1bfaffe702609f2e682e8b1181946d
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/libmapper/Makefile b/libmapper/Makefile
index 128a032..ae6a895 100644
--- a/libmapper/Makefile
+++ b/libmapper/Makefile
@@ -4,7 +4,7 @@
 
 PACKAGE_DEPS=libsystemd
 SONAME=libmapper.so
-VERSION=1
+VERSION=2
 LIBMAPPER=$(SONAME).$(VERSION)
 BIN=mapper
 INCLUDES=mapper.h