Updated Travis-CI conf to avoid 'brew upgrade' error. Using pre-installed xctool instead.
Updated Travis-CI conf to avoid 'brew upgrade' error. Using pre-installed xctool instead.

HyprMXMobile/OHHTTPStubs,danielctull-forks/OHHTTPStubs,tarbrain/OHHTTPStubs,HyprMXMobile/OHHTTPStubs,danielctull-forks/OHHTTPStubs,danielctull-forks/OHHTTPStubs,tarbrain/OHHTTPStubs,HyprMXMobile/OHHTTPStubs,danielctull-forks/OHHTTPStubs,tarbrain/OHHTTPStubs,HyprMXMobile/OHHTTPStubs,tarbrain/OHHTTPStubs