add encryption for uploaded file

For the job posted on https://www.odesk.com/o/jobs/job/_~01385bc81bcb9aafc3/

I am not very familiar with the GAE unit test framework, so I skip the unit test for now. The change has been tested locally on a dev server. 

Tested with the following file.

test@Rays-MacBook-Pro:~/Desktop$ cat test.csv
1, Lei Zhang, python developer
2, Chrise, project owner
3, Tom hanks, movie star