Add keyword search placeholder for MHRA finders

MHRA users think update or alert title is a weird placeholder as they
search for drug or device name.
Merge pull request #78 from alphagov/add-keyword-search-placeholder-for-mhra-finders

Add keyword search placeholder for MHRA finders
Placeholders should be lower case

With the different placeholder for MHRA finders, the placeholder was
incorrectly starting with an uppercase letter.
Merge pull request #79 from alphagov/lower-case-placeholder

Placeholders should be lower case
Add rake task to create all topics on govdelivery

We need to provide the ability for users to sign up for a format, with
filters based on a single field.

This rake task precreates all the necessary topics for each combination
of options. For formats with no options, it will create a single list
for the entire format.
Push signup options to publishing api

finder front end will use these to build the checkbox options for a
format.
Merge pull request #80 from alphagov/email_topic_creation

Create topics on govdelivery for each format
Remove mistakenly committed extra details hashes

ContentItemPresenter was modified by mistake during discussion of how we should
implement this feature.

FinderContentItemPresenter was modified before realising that it inherits from
ContentItemPresenter.
Merge pull request #82 from alphagov/fix-details-hashes

Remove mistakenly committed extra details hashes
Finder beta status in details hash

As more Orgs start using Finders, we want to show to users that the
Finder and it's content are still in Beta.

This commit adds a beta flag to the metadata and is sent as part of the
details hash in the Finder when it's published to the publishing API.
Remove duplicate and re-add details hash to ContentItemPresenter
Merge pull request #81 from alphagov/finder-beta-status-in-details-hash

Finder beta status in details hash