Auto merge of #2216 - jtgeibel:update-aggressive/oauth2, r=JohnTitor

Aggressive update of oath2

```
Updating arrayref v0.3.5 -> v0.3.6
Updating backtrace v0.3.38 -> v0.3.44
Updating backtrace-sys v0.1.31 -> v0.1.32
Updating byteorder v1.3.2 -> v1.3.4
Updating curl v0.4.12 -> v0.4.25
Updating curl-sys v0.4.16 -> v0.4.26
Updating failure v0.1.5 -> v0.1.6
Updating failure_derive v0.1.5 -> v0.1.6
Updating safemem v0.3.0 -> v0.3.3
Updating socket2 v0.3.8 -> v0.3.11
Updating synstructure v0.10.2 -> v0.12.3
Updating typenum v1.10.0 -> v1.11.2
```

r? @JohnTitor

Author: bors