Named truststores, Client builder

[andrus]

The apps occasionally need more than one truststore. Or a typical situation when a client for one endpoint needs a custom trust store (because the server is using self-signed certificates), and all others are fine with the default JVM truststore. So going to replace (with deprecation) the current singleton truststore with a new config tree:

jerseyclient:
   trustStore:
     ts1:
       location: "classpath:ts1"
       password: "changeit" # "changeit"  is the default of course and can be omitted
    ts2:
      location: ....

The use of it will require adding builder method to HttpClientFactory:

clientFactory.newClientBuilder().auth("a1").trustStore("ts1").build();