Merge pull request #5641 from apple/remove_ubuntu_14_15

[README] Remove Ubuntu 14.04 and 15.10 status

Author: shahmishal

README.md

@@ -4,8 +4,6 @@
 || **Swift** | **Package** |
 |---|---|---|
 |**macOS**         |[![Build Status](https://ci.swift.org/job/oss-swift-incremental-RA-osx/badge/icon)](https://ci.swift.org/job/oss-swift-incremental-RA-osx)|[![Build Status](https://ci.swift.org/job/oss-swift-package-osx/badge/icon)](https://ci.swift.org/job/oss-swift-package-osx)|
-|**Ubuntu 14.04** |[![Build Status](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-14_04/badge/icon)](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-14_04)|[![Build Status](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-14_04/badge/icon)](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-14_04)|
-|**Ubuntu 15.10** |[![Build Status](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-15_10/badge/icon)](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-15_10)|[![Build Status](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-15_10/badge/icon)](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-15_10)|
 |**Ubuntu 16.04** |[![Build Status](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_04/badge/icon)](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_04)|[![Build Status](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-16_04/badge/icon)](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-16_04)|
 |**Ubuntu 16.10** |[![Build Status](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_10/badge/icon)](https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_10)|[![Build Status](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-16_10/badge/icon)](https://ci.swift.org/job/oss-swift-package-linux-ubuntu-16_10)|