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
Technically a WebLogic Managed Server can be configured for any of the following keystore modes:
- Demo Identity and Demo Trust: The demonstration identity and trust keystores, located in the MIDDLEWARE_HOME\server\lib directory and the JDK cacerts keystore, are configured by default. Use for development only.
- Custom Identity and Java Standard Trust: A keystore you create and the trusted CAs defined in the cacerts file in the JAVA_HOME\jre\lib\security directory.
- Custom Identity and Custom Trust: Identity and trust keystores you create.
- Custom Identity and Command Line Trust: An identity keystore you create and command-line arguments that specify the location of the trust keystore.

I choose a different container because the settings for each mode are different (e.a. required properties on the container) and because the plugin only supports the third mode. I guess if we were able to support all modes, it would probably more logical to deploy certificates to a WebLogic Server, but this would still pollute the property space of the WebLogic Server container with a lot of properties from all the different keystore modes.