Update README with version requirement for aws-sdk

Fix merge problem with S3 storage

Includes memory usage adjustments.

Conflicts:
	lib/paperclip/storage/s3.rb

Cache interpolator methods and reduce memory allocations - rebased on v4.3

something in aruba 0.10.x is breaking the cucumber specs

Inspected by https://github.com/dkhamsing/frankenstein

[ci skip]

Resolve broken CI tests due to upstream gem changes

something in aruba 0.10.x is breaking the cucumber specs

the name string is used multiple times in interpolation so storing it reduces object creation

this commit primarily uses frozen strings to reduce object creation during interpolation.
the :basename method now uses File.basename(file, ".*") rather than a Regexp. basename may be called multiple times.

by using the attachment name (symbol) and Class as keys we reduce the number of Strings created before hitting the cache

* Regression fix
* Add specs for intermediate_files var in Paperclip::Attachment

[fixes #1908]

Fixed typos

added the comma in line 54

Add context from:
https://github.com/thoughtbot/paperclip/issues/2021

[ci skip]

[ci skip]

Before the error message was sometimes millions of characters long.

> [paperclip] Content Type Spoof: Filename a.csv
> (application/octet-stream from Headers,
> [#<MIME::Type::Columnar:0x007f9f90f89fa8
> @container=#<MIME::Types:0x007f9f90b09d98 ... snip millions of
> characters of output here ...>], @content_type="text/csv",
> @raw_media_type="text", @raw_sub_type="csv", @simplified="text/csv",
> @i18n_key="text.csv", @media_type="text", @sub_type="csv",
> @extensions=["csv"]>] from Extension), content type discovered from
> file command: application/zip. See documentation to allow this
> combination.

Now becomes:

> [paperclip] Content Type Spoof: Filename a.csv
> (application/octet-stream from Headers,
> ["text/comma-separated-values", "text/csv"] from Extension), content
> type discovered from file command: application/zip. See documentation
> to allow this combination.

[fixes #2017]

update README.me: add missing 'end'

Paperclip works well with aws-sdk 1 and 2, and we default to 2.

[ci skip]

  $ rspec spec/paperclip/integration_spec.rb --profile 1
  Testing against version 4.1.7
  ..................................

  Finished in 15.19 seconds (files took 0.60155 seconds to load)
  34 examples, 0 failures

  Top 1 slowest examples (9.54 seconds, 62.8% of total time):
    Paperclip Many models at once does not exceed the open file limit
      9.54 seconds ./spec/paperclip/integration_spec.rb:18

to

  $ rspec spec/paperclip/integration_spec.rb --profile 1
  Testing against version 4.1.7
  ..................................

  Finished in 10.95 seconds (files took 0.59585 seconds to load)
  34 examples, 0 failures

  Top 1 slowest examples (5.33 seconds, 48.7% of total time):
    Paperclip Many models at once does not exceed the open file limit
      5.33 seconds ./spec/paperclip/integration_spec.rb:18

Updates gemfiles to Ruby 2 hash syntax.

[closes #1700]

Remove from Travis JRuby and Rubinius

They are allowed to fail, and they consistently fail. They only add up
time to our builds. If we wanted to keep them, they should be in the
build matrix and run tests successfully.

Removes note for running paperclip in EOL'd version of Rails (2.3).

Removes `column_type` and `column_options` so that it works well in both
versions.

Backcported from master, to release a patch version with this bugfix.

[closes #1947]