Add X-* headers to the event context

[atompie]

Is your feature request related to a problem? Please describe. Some webhooks sent X-* headers that have some information. Add it to the session, or event context.

Describe the solution you'd like All X-* headers end up in a context

[atompie]

It is better to keep it in event context as each event may have different headers.

[atompie]

Done in 0.7.2