Miniral Changes

Miniral Changes
Merge branch 'zz_local'
Merge pull request #60 from alexwolfwang/master

file types selection filter
Junit Test for PlayManager
Junit Test Suite for package Play.
javaDoc comments
Created UnitTesting Suite

All the unitTest Suites will be added to this class 
so that we can run all test as a batch.
code fixed
GridView Bug fixed

GridView Bug fixed
PlayManager Refactored

PlayManager Refactored. Mainly on modifying variable names.
Merge pull request #3 from zhaozheid/master

update