Added backbone perf test

Direct call complexObject.changeText() x 1,091,011 ops/sec ±1.50% (91 runs sampled)
Change via binding x 1,037,611 ops/sec ±1.45% (89 runs sampled)
Change via event notification x 183,537 ops/sec ±1.85% (75 runs sampled)
Merge branch 'master' of github.com:anvaka/jsbind