ensure integrity values of notifications are base64 encoded

[tomkralidis]

Users have reported that some notification messages properties.integrity.value values are not base64 encoded (per the WNM draft), even though they should be. Relevant reference implementations (wis2box, pywis-pubsub) should be updated accordingly.

Many thanks to @allanfrankwork for reporting the issue.

cc @kaiwirt @golfvert

[tomkralidis]

Relevant updates/fixes:

• https://github.com/wmo-im/wis2box/pull/484
• https://github.com/wmo-im/pywis-pubsub/pull/28
• https://github.com/wmo-im/wis2-notification-message/pull/55

[tomkralidis]

Updates:

• pywis-pubsub 0.5.0 released: https://github.com/wmo-im/pywis-pubsub/releases/tag/0.5.0
• wis2box fix will be part of 1.0b5 release

[kaiwirt]

For GC Offenbach and WIS2 Node Offenbach we use the base64 encoding. However we also see WNM without this encoding. Input-wise we support both hex and base64

[golfvert]

To be closed.