Build UberJar

[marctatham]

Added support for constructing an UberJar that contains the ktor app along with ALL dependencies.

Constructing the UberJar is as simple as running the relevant gradle task
./gradlew clean shadowJar

And running the resulting UberJar is as simple as:
java -jar build\libs\ktor-appengine-java11-standardenv-0.0.1-all.jar

C:\Users\Marc\Documents\Dev\marctatham\ktor-appengine-java11-standardenv>java -jar build\libs\ktor-appengine-java11-standardenv-0.0.1-all.jar
2020-04-14 15:36:07.451 [main] TRACE Application - {
    # application.conf @ jar:file:/C:/Users/Marc/Documents/Dev/marctatham/ktor-appengine-java11-standardenv/build/libs/ktor-appengine-java11-standardenv-0.0.1-all.jar!/application.conf: 6
    "application" : {
        # application.conf @ jar:file:/C:/Users/Marc/Documents/Dev/marctatham/ktor-appengine-java11-standardenv/build/libs/ktor-appengine-java11-standardenv-0.0.1-all.jar!/application.conf: 7
        "modules" : [
            # application.conf @ jar:file:/C:/Users/Marc/Documents/Dev/marctatham/ktor-appengine-java11-standardenv/build/libs/ktor-appengine-java11-standardenv-0.0.1-all.jar!/application.conf: 7
            "com.marctatham.ApplicationKt.module"
        ]
    },
    # application.conf @ jar:file:/C:/Users/Marc/Documents/Dev/marctatham/ktor-appengine-java11-standardenv/build/libs/ktor-appengine-java11-standardenv-0.0.1-all.jar!/application.conf: 2
    "deployment" : {
        # application.conf @ jar:file:/C:/Users/Marc/Documents/Dev/marctatham/ktor-appengine-java11-standardenv/build/libs/ktor-appengine-java11-standardenv-0.0.1-all.jar!/application.conf: 3
        "port" : 8080
    },
    # Content hidden
    "security" : "***"
}

2020-04-14 15:36:07.528 [main] INFO  org.eclipse.jetty.util.log - Logging initialized @618ms to org.eclipse.jetty.util.log.Slf4jLog
2020-04-14 15:36:07.644 [main] INFO  Application - No ktor.deployment.watch patterns specified, automatic reload is not active
2020-04-14 15:36:08.016 [main] INFO  Application - Responding at http://0.0.0.0:8080
2020-04-14 15:36:08.020 [main] INFO  org.eclipse.jetty.server.Server - jetty-9.4.24.v20191120; built: 2019-11-20T21:37:49.771Z; git: 363d5f2df3a8a28de40604320230664b9c793c16; jvm 11.0.5+10-LTS
2020-04-14 15:36:09.279 [main] INFO  o.e.jetty.server.AbstractConnector - Started ServerConnector@1750fbeb{HTTP/1.1,[http/1.1, h2c]}{0.0.0.0:8080}
2020-04-14 15:36:09.280 [main] INFO  org.eclipse.jetty.server.Server - Started @2378ms