[fix]Qiu&Xiaofeng: use stub in testing

use stub in reading config file.
[feature]Qiu&Xiaofeng: add testcase for job without config file
[fix]Qiu&Xiaofeng: remove comments in reading config file
[feature]Qiu&Xiaofeng: add e2e testcase for job with config file

would show config file content in a `pre` tag on detail page.