Fix discuss page: js failed when there's no discussion yet

If there's no discuss the server will return null, the script call .length() without validating. From the user's view, the loading icon will remain showing.
add replay support for PC^2 Runs file

use regex to fetch info, may cause performance problem....
fix hustv replay crawler: url changed
Merge pull request #4 from crccw/fix-hustv-replay-crawler

fix hustv replay crawler: url changed
Merge pull request #2 from crccw/fix-discuss-page

Fix discuss page: js failed when there's no discussion yet
Merge pull request #3 from crccw/add-replay-pc2run

add replay support for PC^2 Runs file