ETA Curve 25519?

The newest version of GnuPG (>=2.1.7) supports now Curve 25519 keys for encryption as well, so I figured I get rid of my oversized (8k RSA) PGP-Key and make myself a new one with Curve 25519 keys only. Creation worked like a charm:

```
sec ed25519/0xD7C310C60515D0A7 2016-04-15 [C] [expires: 2018-04-15]
Key fingerprint = 6935 4591 E687 BECC 6EC8 1A7E D7C3 10C6 0515 D0A7
uid [ultimate] xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
ssb ed25519/0x347A5C00EF9384BE 2016-04-15 [S] [expires: 2018-04-15]
ssb cv25519/0x0887E3F321F3EC13 2016-04-15 [E] [expires: 2018-04-15]
```

And most of my apps just syscall gpg2, so no problem there either. But keybase as expected doesn't support it yet:

```
keybase pgp select --multi --no-import
[...]
ERROR ImportKey error: openpgp: invalid data: subkey signature invalid: openpgp: unsupported feature: unsupported oid: 2b060104019755010501
```

I do not want to leave my keybase account keyless - would be kinda useless - so I am interested in a rough estimate when Curve 25519 keys are gonna be supported.

Start with the reported `keybase pgp select --multi --no-import` path and the shown GnuPG-generated key. The issue provides no source files or tests to locate. Done would mean Curve25519 keys can be selected or imported without the reported unsupported OID and invalid subkey signature errors.

Written by the indexing model from the issue text.