temporary-1.2.1: CHANGELOG.md

## 1.2.1

* Limit support to GHC 7.0+
* Add new functions: `writeTempFile,` `writeSystemTempFile,` `emptyTempFile,` `emptySystemTempFile`
* Make sure that system* functions return canonicalized paths
* Modernize the code base, add tests and documentation

## 1.2.0.4

* Update maintainership information
* Fix the docs