Fix integration tests on CI server.

Some of the spawned Lazybones commands were timing out because they were taking
too long to get hold of the Handlebars template engine JAR. The relevant
functional spec now allows sub-classes to set the command timeout, so this has
been increased for the failing test.

I also realised that Betamax wasn't tracking the @Grab calls, so I fixed that
too by adding the proxy info to `LazybonesScriptFunctionalSpec`.