Removing instruction text above filters

We shouldn't have to describe how the UI works like this.
If it's not clear in and of itself, we're doing something wrong.
Let's see how users get on without this instruction.
Merge pull request #115 from alphagov/remove-filter-instruction

Remove instruction text above finder filters
Add missing text class to published after input
Merge pull request #116 from alphagov/add-text-class-to-date-input

Add missing text class to 'Published After' date input