feat(bootstraping): application bootstrapping implementation.

Entry-point to bootstrapping is a rootComponent. The bootstrapping
method, uses the component's selector to find the insertion element in
the DOM, and attaches the component in its ShadowRoot.
feat(compiler): new semantics for `template` attributes and view variables.

- Supports `<div template=“…”>`, including parsing the expressions within
  the attribute.
- Supports `<template let-ng-repeat=“rows”>`
- Adds attribute interpolation (was missing previously)