Update "docker" to use "curl" instead of "wget"

See also https://github.com/docker-library/docker/pull/4.

This fixes download issues that look like:
```
Connecting to test.docker.com (216.137.36.117:443)
wget: error getting response: Connection reset by peer
```

library/docker

@@ -1,9 +1,9 @@
 # maintainer: Tianon Gravi <[email protected]> (@tianon)
 # maintainer: InfoSiftr <[email protected]> (@infosiftr)
 
-1.8.2-rc1: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc
-1.8-rc: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc
-rc: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc
+1.8.2-rc1: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8-rc
+1.8-rc: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8-rc
+rc: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8-rc
 
 1.8.2-rc1-dind: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc/dind
 1.8-rc-dind: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc/dind
@@ -13,10 +13,10 @@ rc-dind: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367
 1.8-rc-git: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc/git
 rc-git: git://github.com/docker-library/docker@5c4db83ebdc26e4303fc3a6adf916367d440eea2 1.8-rc/git
 
-1.8.1: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8
-1.8: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8
-1: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8
-latest: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8
+1.8.1: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8
+1.8: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8
+1: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8
+latest: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.8
 
 1.8.1-dind: git://github.com/docker-library/docker@251cf235760a2ba6db1cf1ddc8ccb3d4da5ec99d 1.8/dind
 1.8-dind: git://github.com/docker-library/docker@251cf235760a2ba6db1cf1ddc8ccb3d4da5ec99d 1.8/dind
@@ -28,8 +28,8 @@ dind: git://github.com/docker-library/docker@251cf235760a2ba6db1cf1ddc8ccb3d4da5
 1-git: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8/git
 git: git://github.com/docker-library/docker@a2614c9b94d3bae7d8d61a7cf4d56a42f6332104 1.8/git
 
-1.7.1: git://github.com/docker-library/docker@a98e0c42a96497670c36f4b2dcad2bcc81f18f35 1.7
-1.7: git://github.com/docker-library/docker@a98e0c42a96497670c36f4b2dcad2bcc81f18f35 1.7
+1.7.1: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.7
+1.7: git://github.com/docker-library/docker@6c4acc40ebc56a539fd33e7799187641dc1e27b0 1.7
 
 1.7.1-dind: git://github.com/docker-library/docker@251cf235760a2ba6db1cf1ddc8ccb3d4da5ec99d 1.7/dind
 1.7-dind: git://github.com/docker-library/docker@251cf235760a2ba6db1cf1ddc8ccb3d4da5ec99d 1.7/dind