add spec to test renaming of table with multiple foreign_key constraints.  

see issue #87 and its pull request
bug fix: rename when table has more than one constraint.

it could choosing the wrong index.
fix references matcher to work even if column names aren't specified.  remove redundant file.
add --rspec command and ARGV to runspecs
bug fix: foreign keys should have a consistent default name.

(also, this uncovered that a spec was creating a duplicate constraint.)
update README history