Test this repository with Travis-CI

[kirill-korniakov]

I want to try to test this repo using Travis-CI. I think it is possible, since right now we only several modules, so tests shouldn't take too much time.

Also, it will be tested on Ubuntu Linux only (but with GCC and Clang), but it is better than nothing (what we have right now).

[ilya-lavrenov]

@kirill-kornyakov, do you still want to do this? because now we have buildbot for testing both Main and Contrib repos

[kirill-korniakov]

You're right, we can close this PR. In fact it could be useful for external forks, but this is not a priority for us.