Remove empty quotes when category is empty.

When category = ""

Should print "category: " to file, current behaviour prints "category:
\"\"".

Latter creates an actual category, with a blank title. All posts created
since this update, without a category explicitly written in `rake`
command, or post directly edited, will belong to this category.

Rakefile

@@ -47,6 +47,7 @@ task :post do
   title = ENV["title"] || "new-post"
   tags = ENV["tags"] || "[]"
   category = ENV["category"] || ""
+  category = category.empty? ? "" : "\"#{category.gsub(/-/,' ')}\""
   slug = title.downcase.strip.gsub(' ', '-').gsub(/[^\w-]/, '')
   begin
     date = (ENV['date'] ? Time.parse(ENV['date']) : Time.now).strftime('%Y-%m-%d')
@@ -65,7 +66,7 @@ task :post do
     post.puts "layout: post"
     post.puts "title: \"#{title.gsub(/-/,' ')}\""
     post.puts 'description: ""'
-    post.puts "category: \"#{category.gsub(/-/,' ')}\""
+    post.puts "category: #{category}"
     post.puts "tags: #{tags}"
     post.puts "---"
     post.puts "{% include JB/setup %}"