Web Push API Encryption with VAPID support.
Updated the crypto module to v0.9.0
ECDH output on P-256 curve must be always 32 bytes .
Added the ability to specify Vapid JWT token expiration
Added a SendNotificationWithContext function that accepts a context for supporting telemetry solutions.
Replaced the JWT library with golang-jwt/jwt.
Fixes #42
Encodes and decodes VAPID base64 keys to ensure they are in the correct format.
Fixes https://github.com/SherClockHolmes/webpush-go/issues/26 Fixes https://github.com/SherClockHolmes/webpush-go/issues/29
Added RecordSize to the Options struct. Limits the record size of the encrypted payload.
Re-exporting the HTTP Client Interface to maintain compatibility with v0.0.1.
List of changes described in: https://github.com/SherClockHolmes/webpush-go/pull/17