Fix Compile Problem

[Yannnnnnnnnnnn]

I have test this under two computers in Ubuntu16.04 System and it works. But it will be better if you look into these changes, because I am not familiar with the CMakeLists.txt

[learnccode]

Thank you for your work. We will update the code as soon as possible. @Yannnnnnnnnnnn

[RemoteSensingFrank]

Thanks for your cooperation and I've read all the changes. I wonder that the does problem caused by the version ofopenmvg, for the header cited in my own program can be compiled successfully. And by the way would you mind be a co-dev for the project.

[Yannnnnnnnnnnn]

Maybe you install the openMVG in the /usr/local/, and I just put the openMVG in a normal folder, which means I don't have any ENV_VAR pointing to the openMVG. Besides, I am very glad to be a co-dev of the project.

[RemoteSensingFrank]

I send collaborator inviation to you.And I hope that we can code in the likely style, by the way I will add some explanation for the key block.

[Yannnnnnnnnnnn]

I have add a .travis.yml and PASS the test on Travis CI

[Yannnnnnnnnnnn]

@RemoteSensingFrank I don't receive your collaborator inviation, would you mind to send that to me one more time?

[RemoteSensingFrank]

sure