Fix typo.

The use of OR equal here would imply that `args[:task_name]` should be set to the
empty string if it did not exist, which is not the intention.
Limit the test SDK (for CI) to the supported SDKs.
Add iOS 7.0 to the supported SDKs for CI.
Require the iOS 7.0 SDK.
Unlink the default appledoc on Travis.

Which is appledoc 2.2, whereas Subliminal requires appledoc 2.1.

Travis didn't use to have any version of appledoc installed by default.
Test against the iOS 7.0 SDK on Travis.