Set socket closing by interruption trace as FINE level

Additional comments, extract exec command default name to constant

Signed-off-by: Emmanuel Bigeon <emmanuel@bigeon.fr>

gclc/src/main/java/fr/bigeon/gclc/prompt/CLIPrompter.java

@@ -198,6 +198,8 @@ public class CLIPrompter {
                 }
 
             } catch (final NumberFormatException e) {
+                LOGGER.log(Level.FINER,
+                        "Unrecognized number. Prompting user again.", e); //$NON-NLS-1$
                 keepOn = true;
                 manager.println(CLIPrompterMessages
                         .getString(PROMPTCHOICE_FORMATERR, 0, index));
@@ -384,6 +386,8 @@ public class CLIPrompter {
                 try {
                     added = addUserChoice(val, chs, index);
                 } catch (final NumberFormatException e) {
+                    LOGGER.log(Level.FINER,
+                            "Unrecognized number. Prompting user again.", e); //$NON-NLS-1$
                     keepOn = true;
                     manager.println(CLIPrompterMessages
                             .getString(PROMPTCHOICE_FORMATERR, 0, index));