Clean amber.js, move RequireJS config piece to load sets.

Looser coupling, helps to separate parts.
extracted some parts from initialize to make it shorter
Merge pull request #901 from herby/moving-shims-to-sets

Clean amber.js, move RequireJS config pieces to load sets.
Merge pull request #902 from herby/refactor-helpers-initialize

extracted some parts from initialize to make it shorter