Bump pinned numpy to 1.10.4

We need to do this to work around an issue with mkl packages shipped with
older version of numpy. See:

  ContinuumIO/anaconda-issues#698 (comment)

for more. Using numpy 1.9.x, the code would build with mkl but ip-diffim
would fail tests because mkl couldn't find all of its libraries and
therefore symbols (would terminate with `python: symbol lookup error`).  See
the above issue for more.

etc/config.yaml

@@ -179,8 +179,8 @@ dependencies:
 #
 pin_versions:
   numpy:
-    build: "==1.9"
-    run:   ">=1.9"
+    build: "==1.10.4"
+    run:   ">=1.10.4"
   python:
     build: "2.7.*"
     run:   "2.7.*"