use https for travis pybids requirement

Author: adelavega

.travis.yml

@@ -87,7 +87,7 @@ before_install:
 
 - travis_retry pip install -r requirements.txt
 - travis_retry pip install grabbit==0.2.6
-- travis_retry pip install git+git@github.com:bids-standard/[email protected]#egg=pybids
+- travis_retry pip install git+https://github.com/bids-standard/[email protected]#egg=pybids
 
 install:
 - travis_retry pip install $EXTRA_PIP_FLAGS -e .[$NIPYPE_EXTRAS]