let ant handle expath dependency download

[duncdrum]

Since CI is using an empty exist and installation via autodeploy, expath dependencies have to be manually installed and moved to autodeploy.

Currently this is handled in a separate step on CI. This could be further optimised either by making the logic on ci more DRY, or by adjusting the build.xml to include the necessary steps.

To maintain offline building abilities, the build + deps procedure should be a separate build target.