Better exception handling

You probably only want to rescue `ArgumentError` here, but certainly nothing more than the default `StandardError`. Rescuing `Exception` can lead to very strange behaviour.

See:
http://www.mikeperham.com/2012/03/03/the-perils-of-rescue-exception/
http://stackoverflow.com/a/10048406/1848

Rakefile

@@ -49,7 +49,7 @@ task :post do
   slug = title.downcase.strip.gsub(' ', '-').gsub(/[^\w-]/, '')
   begin
     date = (ENV['date'] ? Time.parse(ENV['date']) : Time.now).strftime('%Y-%m-%d')
-  rescue Exception => e
+  rescue => e
     puts "Error - date format must be YYYY-MM-DD, please check you typed it correctly!"
     exit -1
   end