Add Gemfile to facilitate local testing

.gitignore

@@ -1,6 +1,8 @@
-
 .DS_Store
 administration.bbprojectd/jgraybeal.bbprojectsettings
 *.bbprojectdata
 administration.bbprojectd/Scratchpad.txt
 administration.bbprojectd/Unix Worksheet.worksheet
+
+# Ruby
+Gemfile.lock

docs/Gemfile

@@ -0,0 +1,16 @@
+source "https://rubygems.org"
+
+gem "github-pages", "~> 219", group: :jekyll_plugins
+
+group :jekyll_plugins do
+end
+
+# Windows and JRuby don't include zoneinfo files, so bundle the tzinfo-data gem and associated library.
+platforms :mingw, :x64_mingw, :mswin, :jruby do
+  gem "tzinfo", "~> 1.2"
+  gem "tzinfo-data"
+end
+
+# Performance-booster for watching directories on Windows
+gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]
+