Update .travis.yml

allow use of new travis-ci infrastructure (4GB + 2 cores) (before 3GB + 1.5 cores)
Update .travis.yml

revert (we need sudo)
up #277 : fusion2d
fix testsuite compilation part I
Merge branch 'develop' of https://github.com/feelpp/feelpp into develop
up #277 : clean obselete code
up #277 : add others tests
fix testsuite compilation part II
Merge branch 'develop' of https://github.com/feelpp/feelpp into develop
Merge branch 'develop' of https://github.com/feelpp/feelpp into feature/faster