add dev update script

dist/update-dev.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+function installRuby {
+	rbMasto=`cat .ruby-version`
+	rbVersions=`rbenv versions`
+
+	# build and install ruby with jemalloc
+	if [[ *$rbMasto* == $rbVersions ]]; then
+		RUBY_CONFIGURE_OPTS=--with-jemalloc rbenv install $rbMasto
+	fi
+}
+
+function installMastoDeps {
+	bundle install -j$(getconf _NPROCESSORS_ONLN)
+	yarn install
+
+	# setup db
+	bundle exec rails db:migrate
+}
+
+installRuby
+installMastoDeps
+
+# Done!
+echo "Setup done! Run 'foreman start' to start sidekiq, streaming, web, and webpack
+	Username: admin@localhost:3000
+	Password: mastodonadmin"