hologram subprocess completes async with grunt task

[akdetrick]

https://github.com/jchild3rs/grunt-hologram/blob/master/tasks/hologram.js#L45

It looks like there's no guarantee that the hologram task has actually completed when grunt-hologram completes.

With larger sets of files for hologram to parse, it's likely that the node process won't complete before grunt begins the next task, making it difficult to use subsequent grunt tasks to manipulate hologram output.

cc @mattkime

[mattkime]

looks like there's already a pull request for this - #6

[jchild3rs]

Merged in and published at version 0.0.7