Remove spurious blog posts which aren't blog posts

[ara4n]

e.g:

https://matrix.org/blog/2017/03/13/amdocs https://matrix.org/blog/2017/03/13/t-mobile https://matrix.org/blog/2017/03/13/ericsson https://matrix.org/blog/2017/03/13/thales https://matrix.org/blog/2017/03/13/mozilla https://matrix.org/blog/2017/05/18/divi-3 https://matrix.org/blog/2017/03/06/twitter https://matrix.org/blog/2017/03/06/sample-slider https://matrix.org/blog/2015/01/29/blog https://matrix.org/blog/2015/01/29/code https://matrix.org/blog/2015/01/29/spec https://matrix.org/blog/2015/01/29/guides https://matrix.org/blog/2015/01/31/posts https://matrix.org/blog/2014/09/02/home

[ara4n]

(these were originally wordpress 'pages', but not posts)