weblogic-certificate plugin

Initial version of the weblogic-certificate plugin

Introduces 2 new Containers:
- CustomTrustKeyStore
- CustomIdentityKeyStore

and 2 Deployables
- TrustCertificateSpec
- IdentityCertificateSpec

and an SSL Channel restart contributor
I don't understand the WebLogic domain model well enough, but do we need this as a separate container? It would not e.g. be possible to map the new deployables to a Domain, WebLogic Cluster or Server?

If we do need this, is there any reason to define it in Java rather than in XML? The latter is probably easier for most users to manage and tweak..?