Remove iRate

Merge branch 'macos-10.13'

Use PNG for screenshots when not using JPEG compression

Merge branch 'crashlytics' into develop

Integrate crash reporter Crashlytics.

Merge branch 'develop'

* Upload images through 'Services' menu.
* Support all different regions of Qiniu storage zone.
* Fix crash on macOS 10.11.
* Update status bar icon.

Merge branch 'develop'

* Support multiple file types including BMP/JPEG/PNG/GIF/TIFF, etc.
* Upload images by screen-capturing or copying.
* Upload images by drag-and-drop.
* Upload images with global shortcut.
* Automatically copying URLs when uploaded.
* Compress images before uploading.
* View uploaded images in 'Upload History'.
* Encrypt sensitive information of image hosts.