Use groonga-talk instead of groonga-users-en
doc: use groonga-talk instead of groonga-users-en
doc ja: use groonga-talk instead of groonga-users-en
Merge pull request #14 from myokoym/use-groonga-talk

Use groonga-talk instead of groonga-users-en for English ML

Patch by Masafumi Yokoyama. Thanks!!!
Groonga::Expression#append_operation supports operation name
Groonga::Expression#append_constant supports operator name
Groonga::Expression#append_object supports operator name
Add 3.1.1 entry
Support Groogna 3.1.1
Remove code for Ruby 1.8
Remove no longer needed YAML workaround
Use the same environment variable in Rakefile and extconf.rb
Remove unused code
Fix a typo

Pointed out by Masafumi Yokoyama. Thanks!!!
doc: translate news
Bump version

3.1.1 ->
3.1.2
    ^
travis: use SF.jp because RubyFroge will shutdown
test: group Record#attributes tests
test: indent
test: remove duplicated information from test names