Auto merge of #221 - servo:travis-cleanup, r=jdm
Auto merge of #221 - servo:travis-cleanup, r=jdm

Specify package dependencies in 'addons' travis.yml section.

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mbrubeck/rust-azure,mbrubeck/rust-azure,servo/rust-azure,servo/rust-azure,mbrubeck/rust-azure,mbrubeck/rust-azure,servo/rust-azure,servo/rust-azure,mbrubeck/rust-azure,servo/rust-azure