Create Holograph-cli module

[Chapabu]

Just an idea.

Instead of (or as well as) having the binary that ships with Holograph, there could be some value in a holograph-cli module that we can use to control it. I'd see it as similar to how gulp-cli and grunt-cli work, in that they're just global module that defer to a local install. Looking forward, this will make things like holograph init simpler, as well as open the doors for things like holograph watch for watching files outside of a task runner, holograph build for building outside of a task runner.