unit-test: Create initial associations file

Make interface more unit testable by moving to separate
file and documenting it.

Change-Id: Ia27f33d706c62a0011790ec94185dd6be3922f21
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/Makefile.am b/Makefile.am
index 62fe99e..668a529 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -26,7 +26,8 @@
 libmapper_la_LDFLAGS = $(SYSTEMD_LIBS) -version-info 1:0:0 -shared
 libmapper_la_CFLAGS = $(SYSTEMD_CFLAGS)
 
-mapperx_SOURCES = src/main.cpp src/argument.cpp src/processing.cpp
+mapperx_SOURCES = src/main.cpp src/argument.cpp src/processing.cpp \
+	src/associations.cpp
 mapperx_LDFLAGS = $(SDBUSPLUS_LIBS) -pthread -ltinyxml2
 mapperx_CXXFLAGS = $(SYSTEMD_CFLAGS) -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_ERROR_CODE_HEADER_ONLY -DBOOST_ALL_NO_LIB