Update of Travis-ci configuration

I reordered the config file for more clarity. I added as well the
installation of coveralls to be sure to run it after the test suite is
successful.

Signed-off-by: Matthieu Berjon <matthieu@berjon.net>

.travis.yml

@@ -1,4 +1,26 @@
 # This file was autogenerated and will overwrite each time you run travis_pypi_setup.py
+env: TRAVIS_DIST=precise
+language: python
+python: 2.7
+
+before_script:
+  - sudo apt-get update -qq
+  - sudo apt-get install -y python3-tk
+
+env:
+  - TOXENV=py27
+
+install:
+  - pip install -U tox coveralls
+language: python
+python:
+  - 3.5
+  - 3.4
+  - 3.3
+  - 2.7
+
+script: tox -e ${TOXENV}
+
 deploy:
   provider: pypi
   distributions: sdist bdist_wheel
@@ -21,14 +43,6 @@ deploy:
     python: 2.7
     repo: mattberjon/fip
     tags: true
-install: pip install -U tox-travis
-language: python
-python:
-- 3.5
-- 3.4
-- 3.3
-- 2.7
-script: tox
 
 after_success:
   - coveralls