Support for configuring trust store

[andrus]

Often we have to read from HTTPS connections that have self-signed certificates (or certificates that are signed by a proper authority, that is unfortunately not known to Java). In this case we need to explicitly tell our clients about those certificates by providing a "trust store". Let's add local trust store to jerseyclient config:

jerseyclient:
  trustStore: classpath:ts.jks
  trustStorePassword: changeit # make this default

[andrus]

TODO: unit tests