Removed unused helpers to clean namespace

Because helpers and decorators is customizable to the user' theme. It's
best for Ecrire to limit the number of predefined helpers so user don't
screw things up. Documentation should say that ApplicationHelper and
OpenGraphHelper are protected namespace.

Or maybe raise an exception if someone tries to use those namespace?
Removed obsolete tests
Added dummy file in shared JS.

The reason is git doesn't allow to commit empty directory. I needed to
add something here as I want the shared/ folder to work and I needed to
resolve #26.

This small welcome has the advangtage of showing the user it can share
code between the blog and the post.

This fix #26.
Fixed issue with RSS Validator.

Some issue with the RSS Validator can't be fixed since the user build a
post by writing HTML code (RSS Validator says there shouldn't be HTML
tags in the content.)
Merge branch 'master' into pothibo.com
Fixed RSS through RSS Validator