Only show user the poems he has created.

Add the user as a poet to the poem he creates.

Add forPoet method to poemsRepository, which returns the poems that are
associated with the specified poet. Call this method from the poem list
instead of the "all" method, so only the poems the poet has access to are
shown. Presently, because there is no mechanism through the UI to add
other poets to a poem, this will only display the peoms the user has
created.
Merge branch 'passport-authentication' into poem-security
Merge pull request #14 from jimguys/poem-security

Poem security