MAINT: Add python 3.7 testing

Author: thequackdaddy

.travis.yml

@@ -23,10 +23,16 @@ matrix:
       env: PANDAS_VERSION_STR="NONE"
     - python: 2.7
       env: PANDAS_VERSION_STR="NONE"
+    - python: 3.7
+      sudo: true
+      dist: xenial
+    - python: 3.7
+      sudo: true
+      dist: xenial
+      env: PANDAS_VERSION_STR="NONE"
 
 # This disables sudo, but makes builds start much faster
 # See http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure/
-sudo: false
 before_install:
   # Work around terrible pathological behaviour in OpenBLAS multithreading, that causes execution time to blow up from 3 minutes to 18 minutes, apparently in SVD on smallish matrices
   - export OMP_NUM_THREADS=1