Revert "experiment with new environment config"

This reverts commit 0349d01.

Author: minggli

.travis.yml

@@ -51,14 +51,14 @@ matrix:
     # In allow_failures
     - dist: trusty
       env:
-        - JOB="3.6, doc" ENV_FILE="environment.yml" DOC=true
+        - JOB="3.6, doc" ENV_FILE="ci/deps/travis-36-doc.yaml" DOC=true
     allow_failures:
       - dist: trusty
         env:
           - JOB="3.6, slow" ENV_FILE="ci/deps/travis-36-slow.yaml" PATTERN="slow"
       - dist: trusty
         env:
-          - JOB="3.6, doc" ENV_FILE="environment.yml" DOC=true
+          - JOB="3.6, doc" ENV_FILE="ci/deps/travis-36-doc.yaml" DOC=true
 
 before_install:
   - echo "before_install"