Add sample data to the package

[miranska]

Upload sample datasets to ./data directory, document and integrate them into examples in the manual. Here is a good tutorial on the process.

[miranska]

@zhangl64, does #9 complete this task?

[zhangl64]

@miranska, partially, the latest version has all data files stored at ./data folder, and they are integrated into examples and help files. However, the data files are not properly documented in the R package. Thus, you will see some warnings when you build the package, but it doesn't stop you from installing and using the package.

[miranska]

OK, then I'll keep it open for now.