DOC: release date revert

Author: jreback

doc/source/whatsnew/v0.17.0.txt

@@ -1,7 +1,7 @@
 .. _whatsnew_0170:
 
-v0.17.0 (July 31, 2015)
------------------------
+v0.17.0 (???)
+-------------
 
 This is a major release from 0.16.2 and includes a small number of API changes, several new features,
 enhancements, and performance improvements along with a large number of bug fixes. We recommend that all