File permission after "cargo login" too permissive

[cesarb]

$ ls -la ~/.cargo
total 16
drwxrwxr-x.  3 cesarb cesarb 4096 Mai 21 22:58 .
drwx------. 43 cesarb cesarb 4096 Mai 21 22:55 ..
-rw-rw-r--.  1 cesarb cesarb   55 Mai 21 22:58 config
drwxrwxr-x.  5 cesarb cesarb 4096 Mai 17 10:51 registry
$ cargo --version
cargo 0.2.0-nightly (efb482d 2015-04-30) (built 2015-04-30)

The permission for either the config file or the directory should not be world-readable, since the config file has the API key for crates.io. It should also complain if it finds an already existing world-readable config file.

[alexcrichton]

Closing as a dupe of #930, but thanks!