Push plugin Guice Module load into the ServerPlugin loader

The responsibility of parsing the Guice Modules list from
Manifest file should be common to all ServerPlugins and
located into the ServerPlugin class.

This allows to avoid duplicates in the parsing and interpretation
of plugin Manifest for all other subclasses of ServerPlugins
provided by other external plugins providers.

Change-Id: If0c8c502517adc53ac30569d6c52e357d3c9f7dd
2 files changed