Remove articles which are now on exciting.io.

We currently have the following Apache redirects in place:

    RewriteRule ^/hello-printer(.*) http://exciting.io/2012/04/12/hello-printer$1 [R=301,L]
    RewriteRule ^/printer-questions(.*) http://exciting.io/2012/05/01/printer-questions$1 [R=301,L]
    RewriteRule ^/printer-kit(.*) http://exciting.io/printer [R=301,L]
    RewriteRule ^/printer(.*) http://exciting.io/printer$1 [R=301,L]
    RewriteRule ^/harmonia(.*) http://exciting.io/harmonia [R=301,L]
    RewriteRule ^/heylist(.*) http://exciting.io/heylist [R=301,L]
    RewriteRule ^/say-hello-to-heylist(.*) http://exciting.io/2013/03/25/introducing-heylist/ [R=301,L]