Merge pull request #3 from xeecos/master

update i2c device's interface
Change example code path

all the example was palced in a subcategory of the library path, there
is no problem if using the older Arduino IDE, but with the arduino
1.0.5, this will cause problems
Merge branch 'master' of https://github.com/JasenWang/Makeblock-Library into jasenWang-master
modify path
fix bug on motor driver example code
Merge remote-tracking branch 'official/master'