Clean code and example

Created by: vtexier

• Change the fix in SigningKey to a better one.
• Change bad g1-test endpoint in examples pointing to ğ1 node port !
• Use SecureBMAEndpoint in examples.

Code ready for a 42.3 release.

Created by: coveralls

Coverage decreased (-0.04%) to 85.99% when pulling 9397d55e on vtexier:dev into 1289d74d on duniter:master.

Seems all good.

added Examples label