User create posts

the params error message thing was a relic I forgot about - so just ignore

A little considered about the DB schema discrepency....
I'd probably break this up into multiple lines for ease of reading:

```ruby
params.
  require(:post).
  permit(:title, :body).
  merge(user: current_user)
```

But to be honest you shouldn't be merging current_user. Instead above you should be doing

```ruby
current_user.posts.new(posts_params)
```