Add scipy to requirements

.test-conda-env-py3.yml

@@ -13,4 +13,5 @@ dependencies:
 - python=3.5
 - symengine=0.3.0
 - python-symengine=0.3.0
+- scipy
 # things not in here: loopy boxtree pymbolic pyfmmlib

requirements.txt

 numpy
 sympy==1.0
+scipy>=0.13
 git+https://github.com/inducer/pymbolic
 git+https://github.com/inducer/islpy
 git+https://github.com/inducer/pyopencl

setup.py

@@ -97,6 +97,7 @@ setup(name="sumpy",
           "boxtree>=2013.1",
           "pytest>=2.3",
           "six",
+          "scipy>=0.13",
 
           # If this causes issues, see:
           # https://code.google.com/p/sympy/issues/detail?id=3874