Create README.md

Create README.md and add the Mozilla wiki link.
Bug 1035045 - Import google protocol buffer

Use google protocol buffer and add comments for each function.
Bug 959118 - Support LayerDump packet

Decode layerdump packet from gecko. However, we still need to
reconstruct the layer tree.
Bug 959118 - Dump layer tree

Reconstuct the layer tree by the layer list and highlight the specific
layer image.
Bug 1073103 - Rename Thebeslayer to PaintedLayer

We substitutes Thebeslayer with PaintedLayer on mozilla-central,
so does Layerscope.