Merge pull request #5372 from minrk/no-close-strings

Don't autoclose strings, because CodeMirror's behavior makes it confusing and awkward to type triple-quoted strings (and these are very common in Python).

An issue about this was filed in CodeMirror itself: https://github.com/marijnh/CodeMirror/issues/2385

IPython/html/static/notebook/js/codecell.js

@@ -102,7 +102,8 b' var IPython = (function (IPython) {'
             mode: 'ipython',
             theme: 'ipython',
             matchBrackets: true,
-            autoCloseBrackets: true
+             // don't auto-close strings because of CodeMirror #2385
+            autoCloseBrackets: "()[]{}"
         }
     };