Created by: abelsromero

This PR fixes #105 (closed) by checking the Ruby language version. If 2.6 or higher, it will replace the rdoc and ri arguments (noew deprecated) by the supported document. Older versions of Ruby runtimes will work same as now.

Only thing I am not confident is that when running mvn clean test -pl gem-maven-plugin -am I get this error gem-maven-plugin: Execution default of goal org.apache.maven.plugins:maven-plugin-plugin:3.4:helpmojo failed: The source must not be a directory. Any idea?

It also:

• Adds Idea files to .gitignore
• Fixes artifactId in rubygems-in-test-resources-failure test. This caused false positives when running all IT tests (those run by maven-invoker-plugin) in a specific order.
• Fixes test include-rubygems-in-test-resources adding the correct dependency. This worked due to previoud comment, but failed when run in isolation.