Bump Spirit dependency

package.json

@@ -97,7 +97,7 @@
     "eslint": "4.19.1",
     "eslint-plugin-ghost": "0.0.24",
     "fs-extra": "4.0.3",
-    "ghost-spirit": "0.0.16",
+    "ghost-spirit": "0.0.17",
     "glob": "7.1.2",
     "google-caja-bower": "https://github.com/acburdine/google-caja-bower#ghost",
     "grunt": "1.0.2",

yarn.lock

@@ -5253,7 +5253,26 @@ ghost-ignition@^2.7.0:
     prettyjson "^1.1.3"
     uuid "^3.0.0"
 
-[email protected], ghost-spirit@>=0.0.16:
+[email protected]:
+  version "0.0.17"
+  resolved "https://registry.yarnpkg.com/ghost-spirit/-/ghost-spirit-0.0.17.tgz#f03f94dc98ed89e614c239664dc4a2fec1049bec"
+  dependencies:
+    autoprefixer "8.2.0"
+    bluebird "^3.4.6"
+    connect-slashes "^1.3.1"
+    cssnano "^4.0.0-rc.2"
+    express "^4.14.0"
+    express-hbs "^1.0.2"
+    ghost-ignition "^2.7.0"
+    gulp-postcss "7.0.1"
+    lodash "^4.15.0"
+    postcss-color-mod-function "2.4.2"
+    postcss-custom-media "6.0.0"
+    postcss-custom-properties "7.0.0"
+    postcss-easy-import "3.0.0"
+    postcss-prefix-selector "1.6.0"
+
+ghost-spirit@>=0.0.16:
   version "0.0.16"
   resolved "https://registry.yarnpkg.com/ghost-spirit/-/ghost-spirit-0.0.16.tgz#bb64ca9f23624850f449ece3150ce42151a6f3ae"
   dependencies: