Change required activesupport to older version (2.3.12) - EXPERIMENTAL
Revert "Change required activesupport to older version (2.3.12) - EXPERIMENTAL"

This reverts commit 4a34a8022ae8f91cf855d134d37ebe000045277a.
Check if a multipart field value responds to :read instead of checking for specific object types
Merge pull request #24 from legolin/master

Change multipart handling to check for object#read instead of specific object types