message: Update 1.12.0 release date in changelog
diff: * There currently is no completion support for package references in csproj files. ([#1156](https://github.com/OmniSharp/omnisharp-vscode/issues/1156))
  -## 1.12.0 _(Not Yet Released)_
  +## 1.12.0 (August 8, 2017)
  #### Debugger
  