Build for Java 8; upgrade dependencies and plugins

In this release, I finally dropped support for Java 7. By building this library for Java 8, I'm able to upgrade dependencies to newer versions that resolve identified vulnerabilities.

Upgrade to the latest release of 'logback'

logback-testng-1.3.5

[maven-release-plugin] copy for tag logback-testng-1.3.5

Upgrade dependencies and plugins (part 2)

This release is a continuation of the project housekeeping contained in the previous release.

Upgrade dependencies and plugins

This release contains no functional changes but is instead focused on project housekeeping.

Upgrade to the latest release of JUnit 4

This release upgrades to the latest release of JUnit 4 (4.13.1)

Add handling for UnsupportedClassVersionError

Catch UnsupportedClassVersionError to avoid instantiation failure, which was causing test runs to fail during start-up.

Fix TestNG version conflict; don't depend on Guava

While working on a different project, I discovered that this appender could trigger version conflicts by loading older versions of TestNG classes. I resolved this issue by replacing direct references to these classes with equivalent code implemented via the Java reflection API.

I also removed the dependence on Google Guava. I was only using one class from this library, for an operation that was easily implemented with standard Java features.

Upgrade to latest dependencies

The primary motivation for this release is to address a vulnerability in Guava 19.0. Upgrading to Guava 28.1-android resolves this. While I was in there, I also upgraded to the latest release of logback (1.2.3) and the latest release of junit (4.12).

Add tool chain, update implementation and dependencies for Java 7

• Added tool chain to ensure compilation against JDK 7
• Added dependency management and plugin management
• Replace Java 8 String.join() with Google Guava Joiner
• Move logback.xml file into the "test" hierarchy so it doesn't get included in the deployed artifact

Set the source and target versions for this library

logback-testng-1.1.0

[maven-release-plugin] copy for tag logback-testng-1.1.0