fix rb_application_controller not_configure render path error
简单整理了一下简体中文。

尚未完成，会找时间完善，估计还需要3～4次才能完成。
Merge pull request #871 from harrywalker/patch-1

translations update for simplfied chinese
typo in locale
Update README.md
Update README.md
fix tooltip url for sub-uri setups
Merge pull request #881 from bpct/fix_not_configure

fix rb_application_controller not_configure render path error
use cached burndown data for statistics calculation. helps #877
Merge pull request #883 from backlogs/bug/877-loadingtime

use cached burndown data for statistics calculation. helps #877
do not use empty cached burndowns
Added test for stories closed before sprint start date
Merge remote-tracking branch 'origin/master' into release_graphs