Rename package to match domain simplejavamail.org

[bbottema]

Now that Simple Java Mail has a proper home (simple-java-mail.org), we should rename the packages and maven groupId to match.

org.codemonkey.simplejavamail -> org.simplejavamail

This should be released as a major release (most likely v4.0.0).

[bbottema]

I created a ticked with oss.sonatype to rename the groupId: https://issues.sonatype.org/browse/OSSRH-23071

[bbottema]

Ticket processed by oss.sonatype. I renamed the package structure and update the pom. With the next release, when everything works, I will close this issue.

[bbottema]

v4.0.0 was released and name change is complete.