Removed Broker implementation
Removed Broker implementation

- Removed Pluggable, Broker, PluginBroker, and PluginSpecBroker from Zend\Loader
- Removed tests and docs for all of the above
- Removed obsolete references to Pluggable everywhere found (was only in
  imports, but never used)
- Removed unused MarkupBroker and MarkupLoader

MadCat34/zend-mvc,turrsis/zend-mvc,ezimuel/zend-mvc,svycka/zend-mvc,ezimuel/zend-mvc,turrsis/zend-mvc,MadCat34/zend-mvc,svycka/zend-mvc