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Add xvfb (X Virtual Framebuffer) virtual screen support for future testing.
According to official Docs at:
http://about.travis-ci.org/docs/user/gui-and-headless-browsers/#Using-xvfb-to-Run-Tests-That-Require-GUI-(e.g.-a-Web-browser)
Merge pull request #1452 from juancarlospaco/patch-1

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Update .travis.yml

Add sip to pip
Merge pull request #1453 from juancarlospaco/patch-2

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Merge pull request #1454 from juancarlospaco/patch-3

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Wildcards * are not allowed on apt-get commands
Merge pull request #1455 from juancarlospaco/patch-4

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Fixes Issue #1416
Merge remote-tracking branch 'upstream/master'
Merge pull request #1456 from diegosarmentero/master

Fixes Issue #1416
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Multiple Fixes and simplification.
Merge pull request #1457 from juancarlospaco/patch-2

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Confirmo que funciona, como minimo con 2.7, 
no se 3.3, pero si falla lo arreglare para este.
Merge pull request #1459 from juancarlospaco/patch-3

Update .travis.yml
running working tests only
Merge remote-tracking branch 'upstream/master'

Conflicts:
	.travis.yml
Merge pull request #1462 from diegosarmentero/master

running working tests only
add python 3 check in resources and fixed tests
Merge pull request #1463 from diegosarmentero/master

add python 3 check in resources and fixed tests