What is a Gem? - Gem are packages that work as standalone application or can be used to enhance functionality of existing application.
Download - Rubygems.org: https://rubygems.org/gems/ccavenue
Source - Github: http://github.com/kishanio/CCAvenue-Ruby-Gem
All the above three are available on the CCAvenue Merchant Dashboard
This should just work fine.
$ gem install ccavenue
Rails Specific Installation.
Call bundle install
$ bundle install
Rails Specific Code
Licence - MIT