Add make recipe for building font-awesome.css

Won't be included in the repo, but is useful in certain cases, for
example when embedding Converse in a web component, the fonts need to be
loaded in the main document.

.gitignore

@@ -19,6 +19,7 @@ dist/converse-no-dependencies-es2015.js
 
 locale.zip
 css/webfonts.zip
+css/font-awesome.css
 
 analytics.js
 inverse-analytics.js

Makefile

@@ -126,7 +126,7 @@ dev: stamp-npm
 ## Builds
 
 .PHONY: css
-css: dev sass/*.scss css/converse.css css/converse.min.css css/website.css css/website.min.css css/fonts.css
+css: dev sass/*.scss css/converse.css css/converse.min.css css/website.css css/website.min.css css/font-awesome.css
 
 css/converse.css:: dev sass
 	$(SASS) --include-path $(BOURBON) --include-path $(BOOTSTRAP) sass/converse.scss css/converse.css
@@ -134,6 +134,9 @@ css/converse.css:: dev sass
 css/website.css:: dev sass
 	$(SASS) --include-path $(BOURBON) --include-path $(BOOTSTRAP) sass/website.scss $@
 
+css/font-awesome.css:: dev sass
+	$(SASS) --include-path $(BOURBON) --include-path $(BOOTSTRAP) sass/font-awesome.scss $@
+
 css/%.min.css:: css/%.css
 	make dev
 	$(CLEANCSS) $< > $@