release candidate v0.1.9

Author: dgoffredo

src/datadog/version.cpp

@@ -3,7 +3,7 @@
 namespace datadog {
 namespace tracing {
 
-#define VERSION "v0.1.8"
+#define VERSION "v0.1.9"
 
 const char* const tracer_version = VERSION;
 const char* const tracer_version_string = "[dd-trace-cpp version " VERSION "]";