Enable checkstyle plugin during the verify maven phase

===== Checking coding style
If you have written any new code, it is highly recommended to validate formatting before submitting a Pull Request.
This might be done by invoking:

 $ mvn checktyle:check

[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.296 s
[INFO] Finished at: 2019-04-25T19:55:17-03:00
[INFO] ------------------------------------------------------------------------
[ERROR] No plugin found for prefix 'checktyle' in the current project and in the plugin groups [com.oracle.weblogic, org.jenkins-ci.tools, org.apache.maven.plugins, org.codehaus.mojo] available from the repositories [local (/Users/dlovison/.m2/repository), -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoPluginFoundForPrefixException