[Continuous Integration] More extensive compiler coverage #1145 - Add more compiler for the Linux Continuous Integration   - gcc 4.8, 5.0, 6, 7   - clang 3.6, 3.7, 3.8, 3.9, 4.0, 5.0 - Launch unit test with cmake ctest in verbose mode for enhanced logging in case of unit test failure.
[Continuous Integration] More extensive compiler coverage #1145
- Add more compiler for the Linux Continuous Integration
  - gcc 4.8, 5.0, 6, 7
  - clang 3.6, 3.7, 3.8, 3.9, 4.0, 5.0
- Launch unit test with cmake ctest in verbose mode for enhanced logging in case of unit test failure.

test more compiler for travis

openMVG/openMVG,openMVG/openMVG,openMVG/openMVG,openMVG/openMVG,openMVG/openMVG