Use coloured output

[mfoo]

The plugin should support Maven's Batch Mode (no colours) and default to using colours if the output is a TTY.

As an example, the NodeJS libyear plugin output looks like this:

The intention is to highlight how outdated each package is when the Maven output is scrolling past.

[mfoo]

This is not so simple - Maven uses SLF4J which has no native support for colour. I may be able to add a different logger implementation to the classpath for the plugin invocation though and have SLF4J use that, not the default one.