Upgrade to Composer 1.0.0 only by detecting version 1.0-dev
Upgrade to Composer 1.0.0 only by detecting version 1.0-dev

`[^ ]*` is necessary because Composer 1.0-dev inserts
ANSI escape sequence for yellow.

craigcitro/travis-build,andyli/travis-build,craigcitro/travis-build,JuliaCI/travis-build,andyli/travis-build,JuliaCI/travis-build