Remove typings ignore

Nobody is using v1 of typings anymore on new projects and 'typings' is the recommended name for the folders of your custom types.
On the other hand the official Visual Studio ignore is not ignoring this folder.

VisualStudio.gitignore

@@ -259,9 +259,6 @@ FakesAssemblies/
 .ntvs_analysis.dat
 node_modules/
 
-# TypeScript v1 declaration files
-typings/
-
 # Visual Studio 6 build log
 *.plg