Add plugins, configure and run test build

Gemfile.lock

@@ -1,6 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    RedCloth (4.3.2)
     addressable (2.8.1)
       public_suffix (>= 2.0.2, < 6.0)
     colorator (1.1.0)
@@ -31,8 +32,14 @@ GEM
       safe_yaml (~> 1.0)
       terminal-table (>= 1.8, < 4.0)
       webrick (~> 1.7)
+    jekyll-compose (0.12.0)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-feed (0.17.0)
+      jekyll (>= 3.7, < 5.0)
     jekyll-sass-converter (3.0.0)
       sass-embedded (~> 1.54)
+    jekyll-textile-converter (0.1.0)
+      RedCloth (~> 4.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     kramdown (2.4.0)
@@ -65,6 +72,9 @@ PLATFORMS
 
 DEPENDENCIES
   jekyll (~> 4.3.2)
+  jekyll-compose (~> 0.12.0)
+  jekyll-feed (~> 0.17.0)
+  jekyll-textile-converter (~> 0.1.0)
 
 BUNDLED WITH
    2.2.33