Use ruby-build for Mastodon, update cookbooks

This uses the ruby_build provider for Mastodon, installing Ruby 2.4.1
currently. It also updates some other cookbooks and the runlists.

nodes/dev.kosmos.org.json

@@ -1,6 +1,7 @@
 {
   "run_list": [
     "kosmos-base",
+    "kosmos-redis",
     "sockethub",
     "sockethub::proxy",
     "kosmos-wordpress",

nodes/staging.kosmos.org.json

@@ -0,0 +1,18 @@
+{
+  "run_list": [
+    "kosmos-base",
+    "kosmos-redis",
+    "kosmos-mastodon",
+    "kosmos-mastodon::nginx"
+  ],
+  "normal": {
+    "postgresql": {
+      "password": {
+        "postgres": "thiscrapaintsafecuznocrypto"
+      }
+    }
+  },
+  "automatic": {
+    "ipaddress": "staging.kosmos.org"
+  }
+}