Remove deprecation warnings

Currently, Active Record recognizes the table in the string, and knows
to JOIN the comments table to the query, rather than loading comments in
a separate query. However, doing this without writing a full-blown SQL
parser is inherently flawed. Since we don't want to write an SQL parser,
we are removing this functionality. From now on, you must explicitly
tell Active Record when you are referencing a table from a string:

    Post.includes(:comments).where("comments.title =
'foo'").references(:comments)
Remove deprecated options from relationships