use UTF-8 to read/write XML streams instead of platform encoding

Author: hboutemy

plexus-container-default/src/main/java/org/codehaus/plexus/configuration/io/XmlPlexusConfigurationReader.java

@@ -20,7 +20,7 @@ public PlexusConfiguration read( InputStream inputStream )
         throws IOException,
             PlexusConfigurationException
     {
-        return read( new InputStreamReader( inputStream ) );
+        return read( new InputStreamReader( inputStream, "UTF-8" ) );
     }
 
     public PlexusConfiguration read( Reader reader )

plexus-container-default/src/main/java/org/codehaus/plexus/configuration/io/XmlPlexusConfigurationWriter.java

@@ -14,7 +14,7 @@ public class XmlPlexusConfigurationWriter
     public void write( OutputStream outputStream, PlexusConfiguration configuration )
         throws IOException
     {
-        write( new OutputStreamWriter( outputStream ), configuration );
+        write( new OutputStreamWriter( outputStream, "UTF-8" ), configuration );
     }
 
     public void write( Writer writer, PlexusConfiguration configuration )