simplified display_authors_expressions.feature, green
add_an_expression.feature: cleaning step
removed step to create a default language in favor of a before hook
small fix
removed unnecessary steps
fixed typo
breaked down add_comments.feature to smaller scenarios, green
breaking down add_an_expression.feature to smaller scenarios
removed unneeded step
grooming steps
grooming browse_expressions_by_language.feature
refactored display_recent_news.feature, green
refactored manage_expressions.feature, green
fixed manage_expressions.feature
added missing step