Update development dependency

[zetachang]

A clean git clone and bundle install failed some tests (on master), it turns out to be some dev dependency unsupported break it.

They are,

• opal-rails since 0.9.0 (which opal 0.8.0 support is dropped)
• react-rails since 1.4.0 (which the latest version is 1.8.2)

I will temporarily lock the dev-deps on master and loosen them after they are supported.

[zetachang]

[Update] Got our rails test passed with opal 0.9 & opal-rails 0.9.0. Further attempt will be making opal test passed with 0.9 setup.

[zetachang]

suppressed by #164