GUACAMOLE-1754: Run unit tests within Docker build.

Dockerfile

@@ -32,6 +32,7 @@ RUN apk add --no-cache                \
         build-base                    \
         cairo-dev                     \
         cmake                         \
+        cunit-dev                     \
         git                           \
         grep                          \
         libjpeg-turbo-dev             \

src/guacd-docker/bin/build-all.sh

@@ -111,5 +111,5 @@ install_from_git "https://github.com/warmcat/libwebsockets" "$WITH_LIBWEBSOCKETS
 
 cd "$BUILD_DIR"
 autoreconf -fi && ./configure --prefix="$PREFIX_DIR" $GUACAMOLE_SERVER_OPTS
-make && make install
+make && make check && make install