In commit f638e5017 we introduced some methods to avoid race conditions
in tests that created debates, proposals or investments.
However, since we don't have a way to effectively make sure we use these
methods in new code, we forgot to do so when adding tests in commits
c483c6036 and 84b88c0ec.
So we're using them now.
There's a chance that this is what was causing multitenancy tests to
fail sometimes; if we don't wait for the request to get the suggestions
to finish, the application might still be dealing with this request when
we make another request to a different subdomain, or when the test has
finished and the tenant has already been deleted.
On my machine, the test "Creating content in one tenant doesn't affect
other tenants" failed about 5% of the time without these changes, and I
haven't been able to reproduce this failure after applying them. Having
said that, it's possible that this is a coincidence and that this test
will fail for a different reason in the future (like `login_as` not
working properly with subdomains).
In order to test that we remove metadata from PDF we need add
"pdf-reader" gem.
With this gem we can check the info from the PDF and ensure that
this info is removed.
