Fix bug of sending notify mail

通知メール送信で不備があった場合に例外エラーでユーザーの処理が阻害され
ないようにする。
Fixed: Can't click comment button
Merge pull request #312 from tnantoka/fix_comment_form

Fixed: Can't click comment button
Show project summary on the top page
Merge pull request #313 from kmiyake/iss-292_navigation_project_from_top_page

Show project summary on the top page
Install and Setup websocket-rails
Show recent comments on the top page
Track add comments
Refresh recent comment with websocket-rails
Merge pull request #316 from kmiyake/iss-173_notify_user_of_comments_are_added

Notify user of comments are added
Tweak design
Implement feature of showing workers list
Tweak design
Add button to reload workers list
Merge pull request #320 from kmiyake/iss-317_feature_of_showing_worker_list

Implement feature of showing workers list
Restrict comments count
Tweak design
Merge pull request #321 from kmiyake/iss-319_restrict_comments_count

Restrict comments count
Fix in the same order on the top page
Tweak design