[Update by Gordon Tsai at Aug 26]
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[Newly Done]
1. [Done-8]

[Done]
1. (tempalately)Use user.json to specified user identity.
2. Server open the material folder depends on user.For example, AOOP's permanent ID is UEE1303，and I took this class in 102B(current ID:1060)，so when I
   view the AOOP material，what I see would be UEE1303/1060.
3. Be able to get file names in dir,but failed to load it to the page.
4. Improved user.json format.
5. Fixed:Failed to get JSON file property .(\handlers\materials.js :Line 92)
6. Fixed:function load_material should be rewrite with async.waterfall or something else,rather than nested structure.(\handlers\materials.js :Line80-148)
7. Fixed:Failed to read files from dir.
8. Fixed:Failed to load file to the page,but it absolutely has got files' name.(\material\content\material.js :Line33)

[Wait for improved]
1.Clean up all of the test code such as "console.log",etc.
2.Disign the page of showing up material files.(It is currently the form of the example in the textbook.)
3.Some useful functions in load_material (\handlers\materials.js) should be separated ,and rewrited into named functions.

[Wait for discussion]
1. Improve the format of user json.
2. (\handlers\material_helper.js Line24)