Reminder: CI upgrade today

Hello All-

Just a reminder that we will be bringing down the CI starting today at noon, California time, to upgrade to Xcode 8 and the associated SDKs. We will also be locking master during the upgrade as we will be pushing back changes for both Swift 3 and Swift 2.3. We have staged as much of the upgrade as possible, so we are hoping for a short downtime, however, it is possible it may take several hours. (We have planned for up to four.) We’ll send out a message when the upgrade is complete.

At this time, we will also be cutting a swift-3.0-preview-2-branch.

As a reminder, once the upgrade is complete, if you are doing development on a Mac, the minimum required Xcode to build Swift from source will be the latest Xcode 8 beta.