Fix gradle URL

[dayvsonsales]

When I tried to execute build-docker.sh the error bellow was given:

Downloading http://services.gradle.org/distributions/gradle-2.11-all.zip

Exception in thread "main" java.lang.RuntimeException: java.io.IOException: Server returned HTTP response code: 403 for URL: http://services.gradle.org/distributions/gradle-2.11-all.zip
	at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:78)
	at org.gradle.wrapper.Install.createDist(Install.java:47)
	at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:129)
	at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
Caused by: java.io.IOException: Server returned HTTP response code: 403 for URL: http://services.gradle.org/distributions/gradle-2.11-all.zip
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1876)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
	at org.gradle.wrapper.Download.downloadInternal(Download.java:59)
	at org.gradle.wrapper.Download.download(Download.java:45)
	at org.gradle.wrapper.Install$1.call(Install.java:60)
	at org.gradle.wrapper.Install$1.call(Install.java:47)
	at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
	... 3 more

This pull request resolves this error by changing HTTP protocol to HTTPS.