Vcs: Denoise *plugin.cpp and reduces scope of constants

Change-Id: If2eb34e8975cca46a52c61d902b89a5f99c757a5
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/subversion/subversionplugin.h

@@ -43,13 +43,10 @@ QT_END_NAMESPACE
 
 namespace Core {
     class CommandLocator;
-    class IVersionControl;
     class IEditor;
 }
 namespace Utils { class ParameterAction; }
 
-namespace VcsBase { class VcsBaseSubmitEditor; }
-
 namespace Subversion {
 namespace Internal {