vendor: update all dependencies except Azure SDK

The Azure SDK doesn't support Go 1.5 anymore. We can't upgrade it until
Go 1.8 comes out.

vendor/golang.org/x/crypto/openpgp/packet/packet.go

@@ -273,8 +273,6 @@ func consumeAll(r io.Reader) (n int64, err error) {
 			return
 		}
 	}
-
-	panic("unreachable")
 }
 
 // packetType represents the numeric ids of the different OpenPGP packet types. See

vendor/golang.org/x/crypto/openpgp/packet/public_key.go

@@ -540,7 +540,6 @@ func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err erro
 	default:
 		return errors.SignatureError("Unsupported public key algorithm used in signature")
 	}
-	panic("unreachable")
 }
 
 // VerifySignatureV3 returns nil iff sig is a valid signature, made by this
@@ -585,7 +584,6 @@ func (pk *PublicKey) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err
 	default:
 		panic("shouldn't happen")
 	}
-	panic("unreachable")
 }
 
 // keySignatureHash returns a Hash of the message that needs to be signed for

vendor/golang.org/x/crypto/openpgp/packet/public_key_v3.go

@@ -216,7 +216,6 @@ func (pk *PublicKeyV3) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (er
 		// V3 public keys only support RSA.
 		panic("shouldn't happen")
 	}
-	panic("unreachable")
 }
 
 // VerifyUserIdSignatureV3 returns nil iff sig is a valid signature, made by this