CITA SDK v20.2.0

• change version naming style to YY.MM.X since CITA has changed it's version naming rule(https://github.com/citahub/cita/releases/tag/v20.2.0)
• add Makefile and update README, move changelog to CHANGELOG.md
• Bump rake from 10.5.0 to 12.3.3 fixes security vulnerability CVE-2020-8130
• migrate repo to citahub
• refactor codes with suggestion from make lint-ruby-code

CITA SDK v0.24.0

• support transaction version = 2
• set default transaction version to 2

CITA SDK v0.23.0

• add getVersion and peersInfo RPC method

CITA SDK v0.22.0

• support CITA v0.22

CITA SDK v0.21.0

• add recover option for decode transaction, for CITA v0.21 provide from in getTransaction rpc call
• rename protobuf Crypto enum

CITA SDK v0.20.0

• Rename to cita-sdk-ruby, rename top module name to CITA

AppChain.rb@0.2.0

[feature] supports CITA 0.20
[update] set default transaction version to 1
[update] change TransactionSinger.decode output type to hash with symbol keys
[update] parse TransactionSinger.decode hash value to hex string if it's bytes.

AppChain.rb@0.1.0

• [feature] sign & unsign transaction
• [feature] support rpc calls
• [feature] support call contract functions