initial Kernel open hijacking
Add Dir::Tmpname implementation from MRI 2.1

The standard library (most notably Tempfile) depend on this
being present in order to function correctly. If it's not there,
Tempfile.create will fail.

It's possible that the entire implementation doesn't have to be
copied wholesale here, but in the meantime, this seems to work.
Silence a Ruby 2.1+ deprecation warning in tests.

Object#respond_to? should take an optional second argument,
or else Marshal complains when attempting to dump/load the object.

I checked, and the second argument has been around since at least
1.8.7, so it doesn't look like this is going to cause problems
in older apps.
Force encoding for binary string literal in the tests.

Ruby < 2.0 interprets string literals as ASCII-8BIT by default, but
>= 2.0 assumes all string literals (and source files) are in UTF-8.
Calling force_encoding ensures this string is interpreted as binary.
Remove rdiscount from Gemspec
Allow filenames with brackets () or [] to be read.
Added a test for unicode file names
Merge pull request #226 from dekz/kernel_hijack

Kernel open hijacking
Merge pull request #228 from dekz/remove_rdiscount

Remove rdiscount from Gemspec
Test with Ruby 2.1.1, but allow it to fail for now.
Ensure that the splat value is an array.

Fixes the tests broken by introducing the Kernel#open monkeypatch.
Merge remote-tracking branch 'furikake/master'

* furikake/master:
  Added a test for unicode file names
  Allow filenames with brackets () or [] to be read.
Force encoding for binary string literal in the tests.

Ruby < 2.0 interprets string literals as ASCII-8BIT by default, but
>= 2.0 assumes all string literals (and source files) are in UTF-8.
Calling force_encoding ensures this string is interpreted as binary.
Mark 2.0.0 and 2.1.1 as both expecting to pass.
Merge remote-tracking branch 'onehub/tempfile-2-1'

* onehub/tempfile-2-1:
  Force encoding for binary string literal in the tests.
  Silence a Ruby 2.1+ deprecation warning in tests.
  Add Dir::Tmpname implementation from MRI 2.1
Ensure there is at least one test for all Ruby versions.