Flesh out protected_endpoint decorator

[davidlmorton]

I'll continue to add to this pull-request.

[coveralls]

Coverage remained the same when pulling a2b5d34 on davidlmorton:master into 7d80778 on mark-burnett:master.

[mark-burnett]

Here is a sketch of a slightly different approach to _parse_request that avoids having multiple return values.

[mark-burnett]

Here is an example of building a signed/encrypted JWT programatically.

[coveralls]

Coverage decreased (-1.96%) when pulling 78d4c16 on davidlmorton:master into 7d80778 on mark-burnett:master.

[mark-burnett]

You're probably still working on this, but you can define a tuple of exception classes that you want to catch, then use it here:

_INVALID_AUTH_EXCEPTIONS = (MissingAutheHeadersError, MalformedAccessTokenError, InvalidSerialization)

<snip>

        try:
            id_token = self._extract_id_token()
        except _INVALID_AUTH_EXCEPTIONS as e:
            return self.exception_map[e.__class__]
        except:
            LOG.exception('Bad things happened')
<snip>

[coveralls]

Coverage remained the same when pulling 4a02b52 on davidlmorton:master into 7d80778 on mark-burnett:master.