Update a String#{to_sym,intern} spec for "+,-"

Follow ticket-9048
See below links

* http://bugs.ruby-lang.org/issues/9048
* https://github.com/ruby/ruby/pull/383#issuecomment-26915103
Improve some special operators specs
Remove outdated special operators
Added spec on Dir.glob matching non-ASCII file paths.
Removed commented out code.
Fixed Dir.glob not matching non-ascii paths.
Added specs on Dir.entries with non-ascii files.
Return properly encoded paths from Dir.entries
Added spec on Array#drop after a shift.
Fixed Array#drop acting incorrectly after a #shift.
Add rb_class_real per #2358
Merge pull request #2946 from razielgn/array-drop-shift-fix

Fixed Array#drop acting incorrectly after a #shift.
Added a C-API lock for Nokogiri.

This makes whatever the issue is in

https://github.com/sparklemotion/nokogiri/issues/1047
https://github.com/rubinius/rubinius/issues/2844

to not manifest during more than 1 hour of 100 threads running in
the repro script in the Nokogiri ticket.

If a bug never appears, does it exist?
Don't use missing config.rb keys. Closes #2949.
Cleanup .gitignore file

Remove some ignore directives for files in the bin directory
that have been removed.

Add ignore directives for files in the bin directory that
are in the repo but were ignored by .gitignore.
Merge pull request #2952 from southerngs/gitignore-cleanup

Cleanup .gitignore file
Merge remote-tracking branch 'razielgn/dir-entries-encoding'
Added more Dir.entries specs.
Added Dir.open spec for :encoding option.
Encoding-related fixes for Dir.