Fix env var forwarding in remote-install, add remote-clean target

Makefile

@@ -22,10 +22,13 @@ content-pull:
 
 # Remote
 remote-install:
-	ssh $(SERVER) "bash -s" < scripts/server-install.sh
+	ssh $(SERVER) "WEBROOT=$(WEBROOT) USER_REPO=$(USER_REPO) bash -s" < scripts/server-install.sh
 
 remote-install-plugins:
 	ssh $(SERVER) "cd $(WEBROOT) && php bin/gpm install $(shell cat plugins.txt | tr '\n' ' ') -y"
 
 remote-upgrade-grav:
 	ssh $(SERVER) "cd $(WEBROOT) && php bin/grav upgrade"
+
+remote-clean:
+	ssh $(SERVER) "cd $(WEBROOT) && php bin/grav clearcache"

README.md

@@ -79,6 +79,7 @@ After `make content-push`, the Git Sync plugin on the server pulls the changes a
 ```
 make remote-install-plugins   # install/update plugins from plugins.txt on server
 make remote-upgrade-grav      # upgrade Grav core on server
+make remote-clean             # clear Grav cache on server
 ```
 
 ## Plugins