Speed up Travis CI build
Speed up Travis CI build

- Disable xdebug - see https://getcomposer.org/xdebug
- Use Github OAuth token if available
- Quote version strings in .travis.yml

teohhanhui/api-platform-core,meyerbaptiste/core,meyerbaptiste/core,soyuka/core,api-platform/core,teohhanhui/api-platform-core,api-platform/core,meyerbaptiste/core,jdeniau/DunglasApiBundle,vincentchalamon/core,leesiongchan/DunglasApiBundle,api-platform/core,soyuka/DunglasApiBundle,teohhanhui/api-platform-core,soyuka/core,soyuka/core,teohhanhui/api-platform-core,soyuka/core,jdeniau/DunglasApiBundle,jdeniau/DunglasApiBundle,api-platform/core,vincentchalamon/core,vincentchalamon/core,teohhanhui/DunglasApiBundle,meyerbaptiste/core,vincentchalamon/core,ahlee2326/DunglasApiBundle,jdeniau/DunglasApiBundle,theofidry/DunglasApiBundle