Use ruby bundler to invoke Jekyll

Change-Id: I263eb42b6c86ceaef5e0706f6b6b4a857ccdc9c8

appinventor/appengine/build.xml

@@ -92,12 +92,19 @@
           unless="Docs.uptodate">
     <!-- We set failifexecutionfails to false so the whole build doesn't fail
          if the developer doesn't have Jekyll set up -->
-    <exec executable="jekyll" failonerror="true" failifexecutionfails="false">
+    <exec executable="bundle" failonerror="true"
+          failifexecutionfails="false"
+          dir="${docs.dir}/markdown" >
+      <arg value="install" />
+      <arg value="--path" />
+      <arg value="vendor/bundle" />
+    </exec>
+    <exec executable="bundle" failonerror="true"
+          failifexecutionfails="false"
+          dir="${docs.dir}/markdown" >
+      <arg value="exec" />
+      <arg value="jekyll" />
       <arg value="build" />
-      <arg value="-s" />
-      <arg value="${docs.dir}/markdown" />
-      <arg value="--layouts" />
-      <arg value="${docs.dir}/markdown/_layouts" />
       <arg value="-d" />
       <arg value="${docs.dir}/html" />
     </exec>

appinventor/docs/markdown/Gemfile.lock

+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.6.0)
+      public_suffix (>= 2.0.2, < 4.0)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.5)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.11.3)
+    forwardable-extended (2.6.0)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.8.5)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 1.14)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (>= 1.7, < 4)
+      safe_yaml (~> 1.0)
+    jekyll-feed (0.11.0)
+      jekyll (~> 3.3)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
+    jekyll-seo-tag (2.5.0)
+      jekyll (~> 3.3)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (1.17.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.3.6)
+    minima (2.5.0)
+      jekyll (~> 3.5)
+      jekyll-feed (~> 0.9)
+      jekyll-seo-tag (~> 2.1)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (3.0.3)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rouge (3.3.0)
+    safe_yaml (1.0.5)
+    sass (3.7.3)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  jekyll (~> 3.8.5)
+  minima (~> 2.0)
+  tzinfo-data
+
+BUNDLED WITH
+   2.0.1