Build uberjar on CI

[jeroenvandijk]

This work is a proof of concept for releasing uberjars via CI

It includes

• a build script for uberjar creation
• a configuration for CircleCI to build the uberjar and release it under artififacts

An example artificat can be found here on CircleCI

The jar can be run after downloading via one of the following commands:

java -jar build/convex-web-0.1.2053-standalone.jar
java -cp build/convex-web-0.1.2053-standalone.jar convex_web.core
java -cp build/convex-web-0.1.2053-standalone.jar clojure.main -m convex-web.core

The latter two variants can start a repl by using the property syntax

java -cp build/convex-web-0.1.2053-standalone.jar -Dclojure.server.repl="{:port,5555,:accept,clojure.core.server/repl}"clojure.main -m convex-web.core