Update travis

[hanzei]

• Add go 1.10 to tests
• Run the newest version, e.g. 0.10.3 instead of 0.10
• Run tests on go:master

[hanzei]

@gobwas Mind giving your thoughts to this?

[gobwas]

Hi @Hanzei, sorry for the delay. Looks good to me.

[gobwas]

By the way, why there are two X and two x (uppercase and lowercase) letters? )) Maybe all x are ok? )

[hanzei]

By the way, why there are two X and two x (uppercase and lowercase) letters? )) Maybe all x are ok? )

Woops, fixed