Try to speed up travis build.

Also only build doc and deploy on specified conditions.

.travis.yml

@@ -14,17 +14,21 @@ install:
   - echo ok
 
 script:
-  - docker run -t -v $PWD:/root/bigflow centos:7.1.1503 bash -c "export MAKEFLAGS='-j 2';yum install sudo -y -q && cd /root/bigflow/build_support && sh -x build_deps.sh && source ./environment && mkdir /root/bigflow/build && cd /root/bigflow/build && cmake .. && make && make release && cd /root/bigflow/bigflow_python/python && PARALLEL_NUM=2 sh run-tests && cd /root/bigflow/doc/ && sh generate_doc.sh"
+  - docker run -t -v $PWD:/root/bigflow centos:7.1.1503 bash -c "export MAKEFLAGS='-j 4';yum install sudo -y -q && cd /root/bigflow/build_support && sh -x build_deps.sh && source ./environment && mkdir /root/bigflow/build && cd /root/bigflow/build && cmake .. && make && make release && cd /root/bigflow/bigflow_python/python && PARALLEL_NUM=4 sh run-tests && cd /root/bigflow/doc/ && sh generate_doc.sh"
 
 
 deploy: 
   - provider: releases
     api_key: $GITHUB_TOKEN
     file: "bigflow_python/output/bigflow_python.tar.gz"
     skip_cleanup: true
+    on:
+      repo: baidu/bigflow
+      tags: true
   - provider: pages
     skip_cleanup: true
     github_token: $GITHUB_TOKEN
     on:
       branch: master
-    local_dir: ./doc/_build/html
+      repo: baidu/bigflow
+    local_dir: ./doc/_build/html