DOC: use current ipython in doc build

Author: jreback

ci/build_docs.sh

@@ -13,9 +13,10 @@ fi
 
 
 if [ x"$DOC_BUILD" != x"" ]; then
+
     # we're running network tests, let's build the docs in the meantim
     echo "Will build docs"
-    pip install sphinx==1.1.3 ipython==1.1.0
+    conda install sphinx==1.1.3 ipython
 
     mv "$TRAVIS_BUILD_DIR"/doc /tmp
     cd /tmp/doc