Check for duplicated dependencies in Travis

[dtolnay]

This currently fails though. 😿

bitflags v0.8.2
├── clap v2.24.2
│   └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx)
└── openssl v0.9.12
    └── native-tls v0.1.2
        └── hyper-native-tls v0.2.2
            └── reqwest v0.6.2
                └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx) (*)

bitflags v0.9.0
└── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx)

serde v0.9.15
└── ndarray v0.9.1
    └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx)

serde v1.0.7
├── chrono v0.3.1
│   └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx)
├── reqwest v0.6.2
│   └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx) (*)
├── serde_json v1.0.2
│   ├── reqwest v0.6.2 (*)
│   └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx) (*)
├── serde_urlencoded v0.5.1
│   └── reqwest v0.6.2 (*)
├── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx) (*)
└── toml v0.4.1
    └── stdx v0.117.0-rc (file:///home/travis/build/brson/stdx) (*)

[dtolnay]

Relevant ndarray issue: rust-ndarray/ndarray#314

[brson]

bitflags

[brson]

I'm going to disable serde on ndarray for now.

[brson]

Rebased. No more serde dupe. Still waiting on clap.