Document requirement for file command.
Update Capistrano Task example for working in 3.x version
Optionally disable inspecting EXIF for orientation
Ensure required validations accepts subclasses
Merge pull request #1515 from quainjn/allow_subclassed_validators

Ensure required validations accepts subclasses
Merge pull request #1514 from pbyrne/configure-disable-exif-orientation

Optionally disable inspecting EXIF for orientation
Merge pull request #1510 from nonninz/fix-capistrano-readme-command

Update Capistrano Task example for working in 3.x version
Merge pull request #1505 from boone/doc_file_requirement

Document requirement for file command.
added :preserve_files notes to the README
Merge pull request #1509 from drewcimino/soft-delete-doc

added :preserve_files notes to the README