Fix Gmail icon

* Add gmail.ico to skin

via https://ssl.gstatic.com/ui/v1/icons/mail/favicon.ico
Fix Gyazo icon

* Add gyazo.ico to skin

via https://gyazo.com/favicon.ico
Fix too small font size in Options
Merge pull request #287 from syoichi/pr40-font

Fix too small font size in Options
Merge pull request #286 from syoichi/pr39-icon

Fix Gmail and Gyazo icons