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.

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.

Typo in readme

Fix typo "defauly" -> "default" in NEWS

The `file` command on OS X takes the --mime-type option, which returns
only the type and not the optional encoding. This is nice, but it's not
portable. Use --mime and strip the encoding off if it's there.

And don't forget this time.

Validators love instances. Seriously, though, this was causing a problem
when the validator was being called and the private "send" didn't have
an instance to work on.

Update README to v4.1 for installation

This will make Travis not waiting for all builds to finish before notify
us the build result.

http://blog.travis-ci.com/2013-11-27-fast-finishing-builds/

Update link to paperclip-meta repository

Ownership of the paperclip-meta repository was transferred from @y8 to @teeparham.

Gemfile.lock.

It resulted with downloading attachment (i.e. from S3) on each
instance validation even when attachment didn't change at all.

Allows a lambda to be passed to decide what format a style should
be processed as

Travis build: retry bundle install on e.g. timeout

There are some file types that the file command doesn't understand.
Notably, files that have a format, but are ASCII-text based (like ruby,
certificates, etc), show up as text/plain. This presents a problem,
because the mime-types gem either doesn't report them at all (as for
.pem files) or reports them differently (as for .rb files).

This change allows a Paperclip.options[:content_type_mapping] hash,
which allows for a mapping of { :pem => "text/plain" } which tells the
spoof detector that this is an OK matchup and to allow it.