fix HeaderExtractor when using accessor in ActiveRecord

This should fix comma-csv/comma#85
fix quoting for filename on Content-Disposition header
Merge pull request #86 from eitoball/fix_header_extractor_with_accessor_in_active_record

Fix HeaderExtractor when using accessor in ActiveRecord
Fixed a bug which occurs when a polymorphic association has a hash parameter specified
add spec for adad91ac917462a363be5773bd38dbaa2f31ed27
rescue was on the wrong line
Merge pull request #83 from epdejager/polymorphic_associations

Polymorphic Associations with hash parameters
add spec for quoted filename
Merge pull request #87 from astevens/master

fix quoting for filename on Content-Disposition header
update TravisCI configuration

* add ruby 2.1.0
* update Rubinius to use 2.1.1, but allow to fail
* list gemfiles
* use matrix to control builds
update rails and mongoid to lastest
add rails 4.1 gems
update TravisCI config
prepare for releasing version 3.2.1
adds collection for creating dynamic fields based on associations