Update go-jose to v2.1.8

glide.lock

glide.yaml

vendor/golang.org/x/crypto/ed25519/ed25519.go

...olang.org/x/crypto/ed25519/internal/edwards25519/const.go

...rg/x/crypto/ed25519/internal/edwards25519/edwards25519.go

vendor/golang.org/x/crypto/pbkdf2/pbkdf2.go

vendor/gopkg.in/square/go-jose.v2/asymmetric.go

vendor/gopkg.in/square/go-jose.v2/cipher/ecdh_es.go

vendor/gopkg.in/square/go-jose.v2/crypter.go

vendor/gopkg.in/square/go-jose.v2/doc.go

vendor/gopkg.in/square/go-jose.v2/encoding.go

vendor/gopkg.in/square/go-jose.v2/jwe.go

vendor/gopkg.in/square/go-jose.v2/jwk.go

vendor/gopkg.in/square/go-jose.v2/jws.go

vendor/gopkg.in/square/go-jose.v2/opaque.go

vendor/gopkg.in/square/go-jose.v2/shared.go

vendor/gopkg.in/square/go-jose.v2/signing.go

vendor/gopkg.in/square/go-jose.v2/symmetric.go