fix(ng2 blueprint): removing slash after /typings/ in gitignore

If the slash is included only the contents of the directory but not the directory itself is excluded/ignored.

(peer reviewed in person)

Author: IgorMinar

addon/ng2/blueprints/ng2/files/gitignore

@@ -18,7 +18,7 @@
 /libpeerconnection.log
 npm-debug.log
 testem.log
-/typings/
+/typings
 
 # e2e
 /e2e/*.js