Make karate unix launcher work from any directory

[parched]

This change means you can run the karate script from any directory, e.g., path/to/karate or if you add it to PATH it should work too.

Previously this would happen.

$ karate-1.0.0/karate --help
Error: Could not find or load main class com.intuit.karate.Main
Caused by: java.lang.ClassNotFoundException: com.intuit.karate.Main

[ptrthomas]

@parched thanks 👍 - do take a look at the jbang option: https://github.com/intuit/karate/tree/master/karate-netty#jbang - would be good to get your feedback on that - we're wondering if in the future, the VS Code extension can "install" karate that way, it may be an interesting option

[parched]

No problem. jbang does look interesting, but for me personally that's just an extra thing to install. I intend to try the VS Code extension, but I need to have everything work from outside the IDE, so pointing to extension to the preinstalled karate is fine for my use case.