Release JDK11 compatible version

[ejboy]

Make Scriptella compile and run on JDK11.

JDK11 is a major release with many breaking changes. It's important to support it since many companies are transitioning to openjdk due to Oracle's updated support terms for JDK.

Issues to resolve:

• Discontinue mail driver (probably replace with shell) due to javax.mail excluded
• JavaScript compat?
  • Also fix ScriptellaDriverITest in Fix JDK 8 Nashorn JavaScript engine integration #2
• Better support for Janino 3
• Add driver for shell command Add driver for shell command #32

[ejboy]

Early preview is available as 1.3-SNAPSHOT https://oss.sonatype.org/#nexus-search;quick~org.scriptella