ACE-445 - allow launcher to set system properties:

- simplified the launcher in the handling and setting of configuration properties:
  * (almost) all configuration properties are now passed to the OSGi framework as 
    framework property, except for properties starting with 'system.', which are
    set as system property;
  * the 'framework.' prefix is deprecated, as it is no longer needed, but the
    launcher still will strip off this prefix if supplied;
  * agent configuration properties are now regarded as framework properties, and
    the agent now uses BundleContext#getProperty() to obtain its configuration
    options;
  * updated and clarified the help text of the launcher.
- allow configuration options to be set as *normal* arguments of the launcher 
  itself, as well as system property, so, '-Dfoo=bar' and 'foo=bar' both will
  work;
- simplified the semantics of the agent with respect to its configuration 
  handling: system properties are now regarded as default values that can be
  superseded by explicitly configured values (through framework properties, or
  explicit configuration). The '.retain' suffix for system properties to always
  supersede framework properties is removed, as it is quite difficult to explain
  and understand how they should work.



git-svn-id: https://svn.apache.org/repos/asf/ace/trunk@1575269 13f79535-47bb-0310-9956-ffa450edef68