Rewrite `signed_in` decorator as to accept permissions

- This is just a simple minded parameterised decorator function
- Accepts a list of permissions, defaults to `['signin']` if set to None
Merge pull request #60 from alphagov/rewrite-signed-in-decorator

Rewrite `signed_in` decorator as to accept permissions
Add blank edit route

For the list page to link to
Add a list of dashboards at 'administer-dashboards' endpoint

- No frills, just an unordered list of links to the edit pages
Change form redirect test to check location of redirect

- Cuts out the inspection of 'pending_dashboard' in the client session (as this was being included but not actually tested in the test)
- Checks that if your permissions are right you get redirected to the administer page, and that's it.

Conflicts:
	tests/admin/test_dashboards.py
Start using the `signed_in` decorator

- get the client returned from the decorator, which now has permissions assigned to it
- pulls out quite a bit of setup code an is *hopefully* more readable
Pep-8
Merge pull request #62 from alphagov/list-dashboards-standalone

List dashboards (standalone)
bump client version to allow update
Add update and edit routes, use build_dict_for_post on update form

Also includes changes to build dict for post to make update work.
Many changes to stagecraft to make this work have already gone in.
Add method to convert get response to form. Add hidden id.

The testing around this shows that the convert into a form and back out
into a post dict does not lose important info.
Add sensible create form things for the update case.