Add .swp files to gitignore.
Add .swp files to gitignore.

Make git ignore .swp files (generated while editing in vim).

Review URL: https://codereview.appspot.com/7309059

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@7669 2bbb7eff-a529-9590-31e7-b0007b416f81

Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,Frankie-666/color-emoji.skia,MatChung/color-emoji.skia,MatChung/color-emoji.skia,Frankie-666/color-emoji.skia,Hankuo/color-emoji.skia,MatChung/color-emoji.skia,Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia,Hankuo/color-emoji.skia,hbwhlklive/color-emoji.skia,Hankuo/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,hbwhlklive/color-emoji.skia,Frankie-666/color-emoji.skia,hbwhlklive/color-emoji.skia,MatChung/color-emoji.skia