feature #160 Show message when no posts found (voronkovich)

This PR was squashed before being merged into the master branch (closes #160).

Discussion
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Show message when no posts found

![Frontend](http://i.imgur.com/GjCyzsE.png)
![Backend](http://i.imgur.com/l3OPaH8.png)

Commits
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634dd27 Show message when no posts found

Author: javiereguiluz