Merge tag '0.10.0' into develop

0.10.0
Separate one big Rakefile into tasks/*.rake files.
CI all branches.
Merge pull request #7 from yasuhito/feature/refactor_rakefile

Feature/refactor rakefile
Update text2048.gemspec

You need curses to run.
Force curses 1.0.1 since it is no-op on pre-2.1.0.
RSpec 3.0.0.
Merge pull request #9 from yasuhito/feature/gemspec

Feature/gemspec
Version bump.
Merge branch 'release/0.10.1'