Update rebar and the Makefile

* Update rebar to a more recent version
  * Update rebar.config for deprecation warnings
  * Allow people to export the REBAR environment variable to use
    their own version of rebar
  * Fixed `make clean`

Makefile

@@ -1,24 +1,24 @@
+REBAR?=./rebar
 
 all: build
 
 clean:
-	./rebar clean
+	$(REBAR) clean
 	rm -rf logs
 	rm -rf .eunit
-	rm test/*.beam
+	rm -f test/*.beam
+
 
 depends:
 	@if test ! -d ./deps; then \
-		./rebar get-deps; \
+		$(REBAR) get-deps; \
 	else \
-		./rebar update-deps; \
+		$(REBAR) update-deps; \
 	fi
 
-build:
-	@if test ! -d ./deps; then \
-		./rebar get-deps; \
-	fi
-	./rebar compile
+
+build: depends
+	$(REBAR) compile
 
 
 etap: test/etap.beam test/util.beam
@@ -26,7 +26,7 @@ etap: test/etap.beam test/util.beam
 
 
 eunit:
-	./rebar eunit skip_deps=true
+	$(REBAR) eunit skip_deps=true
 
 
 check: build etap eunit

rebar.config

@@ -4,7 +4,7 @@
 
 {port_specs, [{"priv/jiffy.so", ["c_src/*.c"]}]}.
 
-{port_envs, [
+{port_env, [
     %% Link the spidermonkey library
     {".*", "CFLAGS", "$CFLAGS -g -Wall"},