Ensure evaluating at_exit block in top level

In IRB context, exit is irb_exit.

[test-unit-users-en:00089] Odd exit error in irb

Reported by Daniel Berger. Thanks!!!
Indent
test-unit-rr 1.0.2 is released!!!
Fix a bug that decolation style description is ignored

GitHub: fixes #45

Reported by PiotrNestor. Thanks!!!
Add --attribute option

It selects target tests by attribute.

[test-unit-users-en:00098] Test description as a test selection mechanism

Suggested by Piotr Nestorow. Thanks!!!
doc: add 2.5.3 entry
gemspec: add missing gem in development dependency
doc ja: translate
doc: add the missing sentence
test-unit 2.5.3 released!
Remove needless v from tag name
test-unit-capybara 1.0.3 is released!
Match file name extension properly.

Before: try to load the file as CSV
  load_data("foo.csvv")
  load_data("foo.csv.gz")

After: raise ArgumentError
  load_data("foo.csvv")
  load_data("foo.csv.gz")
Remove duplicated name
Use self.class
Name invalid data
Remove anonymous name
Raise ArgumentError if no arguments are given.
doc: Add document for Test::Unit::TestCase::ClassMethods.data
Convert "true"/"false" string as Ruby object