Use scala-ci's artifactory and bintray repositories

Aligning with https://github.com/scala/scala/blob/2.11.x/scripts/jobs/integrate/bootstrap#L123,
as updated by scala/scala#4496

Author: adriaanm

conf/repositories

@@ -1,7 +1,7 @@
 [repositories]
-  plugins: http://dl.bintray.com/sbt/sbt-plugin-releases/, [organisation]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]
-  private-repo: http://private-repo.typesafe.com/typesafe/scala-release-temp/
-  typesafe-ivy-releases: http://repo.typesafe.com/typesafe/ivy-releases/, [organization]/[module]/[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly
-  sbt-plugin-releases: http://scalasbt.artifactoryonline.com/scalasbt/sbt-plugin-releases, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]
+  private-repo: https://scala-ci.typesafe.com/artifactory/scala-release-temp/
+  jcenter-cache: https://scala-ci.typesafe.com/artifactory/jcenter/
+  typesafe-ivy-releases: https://dl.bintray.com/typesafe/ivy-releases/, [organisation]/[module]/[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly
+  sbt-plugin-releases: https://dl.bintray.com/sbt/sbt-plugin-releases/, [organisation]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]
   maven-central
   local