Using travis-xcodebuild with multiple schemes fails

[yoiang]

See: Travis result for commit.

When specifying multiple scheme items, rather than building them separately and in parallel like Travis' xctool integration does or building them one at a time in one job, travis-xcodebuild fails with:

xcodebuild: error: Unknown build action 'Podspec Lint]'.

where Podspec Lint is the second scheme