move database schema upgrade from installation to 'before script'

.travis.yml

   - "pip install -r install/requirements.txt; echo"
   - "./bin/tg2env-patch 2 /home/travis/virtualenv/python3.2.5/lib/python3.2/site-packages"
   - "pip install coveralls"
-  - "cd tracim && gearbox migrate upgrade"
-  
+
 before_script:
   - "psql -c 'create database tracim_test;' -U postgres"
   - "cp tracim/development.ini.base tracim/development.ini"
+  - "cd tracim && gearbox migrate upgrade"
 
 # command to run tests
 script: "cd tracim && nosetests -v --with-coverage --cover-package=tracim --cover-erase"