Adjust to libsyntax API change

[dgrunwald]

This fixes a compiler error on current nightly:

src/lib.rs:36:48: 36:67 error: mismatched types:
 expected `&str`,
    found `syntax::parse::token::InternedString`
(expected &-ptr,
    found struct `syntax::parse::token::InternedString`) [E0308]
src/lib.rs:36                             new_ident.push_str(ident.name.as_str());
                                                             ^~~~~~~~~~~~~~~~~~~

[dgrunwald]

Could you apply this fix and publish a new version of the package on crates.io?

I'm using interpolate_idents in rust-cpython and would like to release a new version that works with the latest rustc nightly.

[SkylerLipthay]

I'm genuinely didn't see this until now! I'm very sorry for the delay, I'll merge this immediately. Thank you for the PR!

[SkylerLipthay]

Published to crates.io. Thanks again! 😄