Remove duplicated 'guard bundler' section.
Merge tag '0.6.0' into develop

0.6.0
Always notify build success.
Fix indentation level.
Merge remote-tracking branch 'origin/develop' into develop
Update bundled gems.
Add FeaturesReply and its test skeletons.
Reduce the complexity of Pio::Icmp::Request#initialize.
Remove duplicated code.
Update README.md with the refactored DHCP examples.
Use the `key: value' style hash syntax.
Merge branch 'develop' into feature/features_reply
Add Pio::Hello YARD comments.
Validate the argument of Pio::Hello.new.
Merge pull request #69 from trema/feature/hello_doc

Feature/hello doc
Merge branch 'develop' into feature/features_reply
Hello -> Pio::Hello in YARD comments.
Hello.read raises Pio::ParseError instead of BinData's exceptions.
Add Echo YARD comments.
Hello -> Pio::Hello in YARD comments.