Fixes #1550

Remove typo in contributing guidelines

Remove extraneous 'not'.

added :preserve_files notes to the README

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

Add german locale file

Locale file for spanish

* Extract private methods
* Remove trailing conditionals
* Remove explicit returns
* Remove `.self`

Add docs badge to README

There's nothing they can be spoofing, and there's little danger of a
webserver accidentally sending a dangerous Content-Type with a file that
has no extension. If the browser chooses to interpret it in a dangerous
manner, no server-side library on earth can change that.

This isn't specifically related to RSpec, but is built off the branch
and is part of an effort to get the CI build green.

First off, sqlite3 needs to be exactly v1.3.8.
Need to make sure both racc and rubysl are in the Gemfiles.
RBX's File.join doesn't like nil at all.
RBX also doesn't like to remove a constant that doesn't exist yet.

There were a bunch of free-floating methods in spec_helper. They were
pulled over from test/helper, but they shouldn't be there. Move them
into appropriate modules in spec/support. This commit also cleans up the
"should_accept/reject_dummy_class methods in favor of using proper
matchers directly. This commit should probably not get squashed or git
will likely forget that those matcher specs are the same file because of
how much changed.