Allow plugins to include assets in the bundle (#28)

Makefile

@@ -4,6 +4,9 @@ NPM ?= $(shell command -v npm 2> /dev/null)
 CURL ?= $(shell command -v curl 2> /dev/null)
 MANIFEST_FILE ?= plugin.json
 
+# You can include assets this directory into the bundle. This can be e.g. used to include profile pictures.
+ASSETS_DIR ?= assets
+
 # Verify environment, and define PLUGIN_ID, PLUGIN_VERSION, HAS_SERVER and HAS_WEBAPP as needed.
 include build/setup.mk
 
@@ -94,6 +97,9 @@ bundle:
 	rm -rf dist/
 	mkdir -p dist/$(PLUGIN_ID)
 	cp $(MANIFEST_FILE) dist/$(PLUGIN_ID)/
+ifneq ($(wildcard $(ASSETS_DIR)/.),)
+	cp -r $(ASSETS_DIR) dist/$(PLUGIN_ID)/
+endif
 ifneq ($(HAS_SERVER),)
 	mkdir -p dist/$(PLUGIN_ID)/server/dist;
 	cp -r server/dist/* dist/$(PLUGIN_ID)/server/dist/;