Don't leak streams when installing aliases.

Change-Id: I31ee806e231fad5f81c55aaa51e90728c2a031b5
Fixes-Issue: CLIENT-522
Reviewed-on: http://gerrit.dmdirc.com/3644
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>

src/com/dmdirc/commandparser/aliases/DefaultAliasInstaller.java

 import com.dmdirc.logger.Logger;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
 
     @Override
     public void migrate() {
-        try {
-            Files.copy(getClass().getResourceAsStream("defaults.yml"), target);
+        try (final InputStream stream = getClass().getResourceAsStream("defaults.yml")) {
+            Files.copy(stream, target);
         } catch (IOException ex) {
             Logger.appError(ErrorLevel.MEDIUM, "Unable to extract default aliases", ex);
         }