homebrew formula: restrict uploading to travis
homebrew formula: restrict uploading to travis

uploading is now only triggerd if a TRAVIS_BUILD_ID environment variable is set
this is normally not the case for normal users, which are trying to build this from source
with the homebrew formula and passing (for whatever reason) --with-dist
[skip ci]

kamilion/starcheat,kamilion/starcheat,chrmoritz/starcheat,R2pChyou/starcheat,wizzomafizzo/starcheat,chrmoritz/starcheat,wizzomafizzo/starcheat,R2pChyou/starcheat