Users can search by region, category, and title

@maneyt @amZotti 
How about this:

```ruby
def show
  @posts = searched_posts
end

private

def searched_posts
  posts = Post
  search_terms.each do |term|
    posts = posts.where(condition, term|
  end
  posts
end

def condition
  "search_cache ILIKE ?"
end
```