allow a user to sign up for an advisory subscription using an existing company if the user (id'ed by email) is already a member of that advisory team. related to https://github.com/GigaOM/legacy-pro/issues/4731
redirect existing subscribers to the lost-password page; related to https://github.com/GigaOM/legacy-pro/issues/4731
fixed a typo
Merge pull request #70 from wluo/github-4731

allow a user to sign up for an advisory subscription using an existing company if the user (id'ed by email) is already a member of that advisory team