Create gradle task that can download dependencies to mavenLocal

[mikehardy]

Once the needed dependencies are available outside of jcenter #1

Write gradle task that:

• takes a list of some sort that specifies on artifact per entry plus coordinates for fetch (likely just URL to compressed bundle that expands directly to maven-compatible dependency tree)
• fetches each and expands it in mavenLocal

It needs an "API" such that simply adding the file as an apply ... script one-liner in a build.gradle works to make it pre-download everything