BLD: Tag empyrical conda packages with numpy version

conda/empyrical/meta.yaml

@@ -12,14 +12,14 @@ requirements:
   build:
     - python
     - setuptools
-    - numpy >=1.9.2
+    - numpy x.x
     - pandas >=0.16.1
     - scipy >=0.15.1
     - bottleneck >=1.0.0
 
   run:
     - python
-    - numpy >=1.9.2
+    - numpy x.x
     - pandas >=0.16.1
     - scipy >=0.15.1
     - bottleneck >=1.0.0