Merge pull request #1974 from Carreau/notebook-path-completion

Allow path completion on notebook.
add slash (/) for unix,  backslash (\) and colon (:) for windows
as authorized characters in completions.

IPython/frontend/html/notebook/static/js/completer.js

@@ -104,7 +104,7 @@ var IPython = (function (IPython) {
 
         // we need to check that we are still on a word boundary
         // because while typing the completer is still reinvoking itself
-        if (!/[0-9a-z._]/i.test(pre_cursor)) {
+        if (!/[0-9a-z._/\\:~-]/i.test(pre_cursor)) {
             this.close();
             return;
         }