Consider adding deferred and traversal / recursive application to material component. #3155
Description
Per Slack discussion
https://aframevr.slack.com/archives/C0GG937RN/p1507698939000005?thread_ts=1507678947.000225&cid=C0GG937RN
We may want the material component to act after object3dset or model-loaded, and to optionally traverse the model and its children, or apply recursively to the object hierarchy. (Though we should consider whether to traverse into child A-frame entities then)