Merge tag '0.8.1' into develop

0.8.1
Update docs badge in README

Update the URL of the docs badge to include it from inch-ci.org instead of inch-pages.github.io (the former being the successor of the Inch Pages project).

[ci skip]
Merge pull request #76 from rrrene/patch-2

Update docs badge in README
Update bundled gems.
Merge pull request #79 from trema/feature/update_gems

Update bundled gems.
added openflow messages
Merge pull request #80 from shun159/openflow_data

added openflow messages
Update bundled gems.
Merge pull request #83 from trema/feature/bundle

Update bundled gems.
Update inch.
Do not use the immediate value 0 (OFPT_HELLO).
Add tests of pio/open_flow/type.rb.
Merge pull request #84 from trema/feature/refactor_hello

Do not use the immediate value 0 (OFPT_HELLO).
Refactor Echo::{Request, Reply}.
Merge pull request #85 from trema/feature/refactor_echo

Refactor Echo::{Request, Reply}.
Add HoundCI configuration file.
Remove Format.create_from methods.
Remove unnecessary private method.
Merge pull request #86 from trema/feature/refactor_echo

Remove Format.create_from methods.
Refactor Hello.new.