Upgrading server package dependencies (#12559)

vendor/github.com/disintegration/imaging/.travis.yml

@@ -1,10 +1,8 @@
 language: go
 go:
-  - "1.7.x"
-  - "1.8.x"
-  - "1.9.x"
   - "1.10.x"
   - "1.11.x"
+  - "1.12.x"
 
 before_install:
   - go get github.com/mattn/goveralls

vendor/github.com/disintegration/imaging/README.md

@@ -129,6 +129,35 @@ Original image                     | Saturation = 30
 -----------------------------------|----------------------------------------------|---------------------------------------------
 ![srcImage](testdata/flowers_small.png) | ![dstImage](testdata/out_saturation_p30.png) | ![dstImage](testdata/out_saturation_m30.png)
 
+## FAQ
+
+### Incorrect image orientation after processing (e.g. an image appears rotated after resizing)
+
+Most probably, the given image contains the EXIF orientation tag.
+The stadard `image/*` packages do not support loading and saving
+this kind of information. To fix the issue, try opening images with
+the `AutoOrientation` decode option. If this option is set to `true`,
+the image orientation is changed after decoding, according to the
+orientation tag (if present). Here's the example:
+
+```go
+img, err := imaging.Open("test.jpg", imaging.AutoOrientation(true))
+```
+
+### What's the difference between `imaging` and `gift` packages?
+
+[imaging](https://github.com/disintegration/imaging)
+is designed to be a lightweight and simple image manipulation package.
+It provides basic image processing functions and a few helper functions
+such as `Open` and `Save`. It consistently returns *image.NRGBA image 
+type (8 bits per channel, RGBA).
+
+[gift](https://github.com/disintegration/gift)
+supports more advanced image processing, for example, sRGB/Linear color
+space conversions. It also supports different output image types
+(e.g. 16 bits per channel) and provides easy-to-use API for chaining
+multiple processing steps together.
+
 ## Example code
 
 ```go

vendor/github.com/disintegration/imaging/adjust.go

@@ -91,11 +91,12 @@ func AdjustContrast(img image.Image, percentage float64) *image.NRGBA {
 
 	v := (100.0 + percentage) / 100.0
 	for i := 0; i < 256; i++ {
-		if 0 <= v && v <= 1 {
+		switch {
+		case 0 <= v && v <= 1:
 			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*v) * 255.0)
-		} else if 1 < v && v < 2 {
+		case 1 < v && v < 2:
 			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*(1/(2.0-v))) * 255.0)
-		} else {
+		default:
 			lut[i] = uint8(float64(i)/255.0+0.5) * 255
 		}
 	}