Added Blob methods for blob extraction

Implemented blobs() method using connected component labeling algorithm . An experimental blob extraction method is also added. Here are the test results i was able to achieve:

![hen](https://f.cloud.github.com/assets/3799830/1103589/f604e364-18b5-11e3-871f-532bbb3e7b2a.jpg)

![blob](https://f.cloud.github.com/assets/3799830/1103590/01815b6e-18b6-11e3-920e-5faa26c8d26b.png)

![para](https://f.cloud.github.com/assets/3799830/1103593/153f553e-18b6-11e3-836c-61a7f426046d.jpg)

![blob2](https://f.cloud.github.com/assets/3799830/1103594/1ffee0b6-18b6-11e3-8b9f-8565b2f8fe79.png)

![berry](https://f.cloud.github.com/assets/3799830/1103595/2e72c964-18b6-11e3-92df-6180683a5517.jpg)

![blob3](https://f.cloud.github.com/assets/3799830/1103596/41d0bf02-18b6-11e3-8019-4144e6653a6e.png)

![shape](https://f.cloud.github.com/assets/3799830/1103597/5092b27a-18b6-11e3-804a-9b71f25e38e3.jpg)

![blob4](https://f.cloud.github.com/assets/3799830/1103598/594e757a-18b6-11e3-9084-5e5dbcad44db.png)

![5](https://f.cloud.github.com/assets/3799830/1103600/68d76060-18b6-11e3-9ca2-99cb7397c6bf.jpg)

![blob7](https://f.cloud.github.com/assets/3799830/1103602/727a3994-18b6-11e3-8c79-944c45a51aae.png)

![hand](https://f.cloud.github.com/assets/3799830/1103604/8f338680-18b6-11e3-836d-070b8a4a9586.jpg)

![blob6](https://f.cloud.github.com/assets/3799830/1103606/971895ac-18b6-11e3-9a4c-e070db7db253.png)