Dependencies should support multiple names

I'm delaying this to the next release.

This is actually much more difficult than it seems, because you suddenly get into a situation where you can have nested arrays sent to the client, and since #111 hasn't been fixed yet, nested arrays will break the dependency parameters.

For instance:

  service { yay: require => [File[one,two], File[three]] }

This would compile down to:

[[["file", "one"], ["file", "two"]], ["file", "three"]]

The only solution I can think of is to flatten all arrays in the compiled result before I send it to the client (I have to wait until the last minute, else people could not use nested arrays in things like templates), but even that probably wouldn't work because it would have to be smart enough to know which arrays to flatten and how much (i.e., relationship params *expect* nested arrays, but they have to be set up a specific way).

#448 should hopefully make this mostly obsolete, but it's probably a ways away.