Merge pull request #1173 from apahim/test_travis_v2

Fix travis build for python2.6

requirements-travis.txt

 # All pip installable requirements pinned for Travis CI
-fabric==1.10.0
+fabric==1.11.1
 pystache==0.4.1; python_version < '2.7'
 pystache==0.5.4; python_version >= '2.7'
 Sphinx==1.3b1

requirements.txt

 # Avocado functional requirements
 # SSH lib (avocado.utils.remote)
-fabric>=1.7.0
+fabric>=1.11.0
 # multiplexer (avocado.core.tree)
 PyYAML>=3.11
 # vm plugin (avocado.core.plugins.vm)