Cucumber needs to tell FakeWeb the s3_domain_url path for uploading a file, and FakeWeb needs to return XML

* update aruba methods for in_current_dir and check_file_presence
* switch rspec syntax from should to expect
* configure raise_in_transactional_callbacks if AR >= 4.2
* remove paperclip itself from Appraisal
This also updates Travis to use the default bundler (to enable caching) and to build primary rubies first

Mime-types 2.6.1+ has a columnar store that only loads the data that is
needed for a drastically reduced memory footprint.
cc/ @jeremyevans @halostatue

See: https://github.com/mime-types/ruby-mime-types/pull/96.

[fixes #1873]

Also, add integration tests for custom processor definition and unit
test for Paperclip.load_processor (thoughtbot/paperclip#1535).

File.exists? has been deprecated since Ruby 1.9.2

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.

This is a big one.

This change converts all of the existing tests from test/unit to RSpec.
It's been a long time coming, and was specifically prompted by the
inability of minitest to work with Appraisal across the various Rails
versions. Instead of ironing out that headache, converting to RSpec was
preferable (after initial probing).

Many assertions are still assertions and are housed in the Assertions
module, but they should be converted as they get touched. Similarly,
since we're touching all the tests/specs, we convert all the hashes from
1.8 syntax to 1.9 syntax.

It is now a requirement for attachments to do one of three things:
  1. Have a content_type validation (e.g. "image/*")
  2. Have a filename validation (e.g. *.png, *.gif)
  3. Explicitly *not* have one of those validations

The intent is to make the default more secure, and you have to
explicitly reject the security of a validation in order to not have one.

There was a spec that was failing because we removed .attachment_definitions
from models, I expected this to fix it, but apparently it hasn't.

This is for Rails 3.1+

Needs work for S3 Attachments.

This is necessary so Gemnesium will be green.

The original commit came from @amazonwebservices and @trevorrowe in #579.
I had to revise the commit and make sure all the test cases are passing.
All credits still goes to those guys, thanks a lot!

This will fix the problem on the CI server, where some time the change occurred by "write_file" will not trigger Rubinius to generate a compiled .rbc file.

This test will generate a basic Rails application, include Paperclip
into Gemfile, and call basic `has_attached_file` in the model. This will
make sure that we're not messing up any of the configuration and
integration for our gem and the Rails framework.