Merge pull request #3 from julycoding/master

Merge master code to my own repo
Merge pull request #4 from julycoding/master

Merge master code to my own repo
Merge pull request #5 from julycoding/master

Merge master code to my own repo
Merge pull request #6 from julycoding/master

Merge master code to my own repo
Merge pull request #7 from julycoding/master

Merge master code to my own repo
Merge pull request #8 from julycoding/master

Merge master code to my own repo
Merge pull request #9 from julycoding/master

Merge master code to my own repo
Merge pull request #10 from julycoding/master

Merge master code to my own repo
Add Python code file for chapter 02
Merge pull request #67 from BrickXu/master

Add Python code file for chapter 02