PullRequest: Fix code comment to work in overview

"Show commentbox" button has not worked.
fix notification filtering bug
Merge branch `fix/cannot-open-line-comment-box-in-pullrequest-overview` of npcode/yobi

from pull request 288
Issue: modify assinee name on assign event
Merge branch `issue/error-assinee-toolip` of insanehong/hive

from pull request 314
docs: Add system requirements
fix: replace 'nforge' with 'yobi'
Merge branch `bugfix/notification` of kjkmadness/yobi

from pull request 310
Merge branch `docs/system-requirements` of npcode/yobi

from pull request 315
Merge branch `fix/remove-nforge` of npcode/yobi

from pull request 316
pullRequest: code refactoring

- add ValidationResult inner class
- method extraction
   - createNewPullRequest
   - getPullRequestMergeResult
- use HttpUtil.isRequestedWithXHR
Constants: remove unused import
Merge branch `pullrequest-refactoring` of alecsiel/yobi

from pull request 312
Label: split LabelEditor.js with Label.js
Label: fix incorrect onClick handler
gitignore: add *.DS_Store to .gitignore for OSX
Merge branch `yobi-568` of laziel/yobi

from pull request 307