Don't git submodule add vterron/barycorr

Travis CI clones Git submodules by default:
https://docs.travis-ci.com/user/customizing-the-build#git-submodules

Author: Víctor Terrón

.travis.yml

@@ -18,7 +18,7 @@ before_install:
   - sudo easy_install -U distribute
   - sudo pip install "numpy>=1.7.1"
   - sudo pip install -r pre-requirements.txt
-  - git submodule add -b init [email protected]:vterron/barycorr.git
+  - cd barycorr; git checkout init; cd ..
   # 'travis_wait': avoid timeout during SciPy installation
   - travis_wait 45 sudo pip install -r requirements.txt
   # Install IRAF and SExtractor