Add command option for whether to require auth credentials

zanata-client-commands/src/main/java/org/zanata/client/commands/ConfigurableOptions.java

@@ -58,4 +58,11 @@ public interface ConfigurableOptions extends BasicOptions {
 
     public
             void setDisableSSLCert(boolean disableSSLCert);
+
+    /**
+     * Use to disable check for presence of username and API key before running command.
+     * 
+     * @return true if this command should fail when username or API key is absent.
+     */
+    public boolean isAuthRequired();
 }

zanata-client-commands/src/main/java/org/zanata/client/commands/ConfigurableOptionsImpl.java

@@ -137,4 +137,9 @@ void setDisableSSLCert(boolean disableSSLCert) {
         this.disableSSLCert = disableSSLCert;
     }
 
+    @Override
+    public boolean isAuthRequired() {
+        // auth should be required for most commands
+        return true;
+    }
 }

zanata-client-commands/src/main/java/org/zanata/client/commands/ListRemoteOptionsImpl.java

@@ -17,4 +17,8 @@ public String getCommandDescription() {
         return "Lists all remote documents in the configured server/project/version.";
     }
 
+    @Override
+    public boolean isAuthRequired() {
+        return false;
+    }
 }

zanata-client-commands/src/main/java/org/zanata/client/commands/PublicanPullOptionsImpl.java

@@ -73,4 +73,8 @@ public void setExportPot(boolean exportPot) {
         this.exportPot = exportPot;
     }
 
+    @Override
+    public boolean isAuthRequired() {
+        return false;
+    }
 }

zanata-client-commands/src/main/java/org/zanata/client/commands/pull/PullOptionsImpl.java

@@ -164,4 +164,9 @@ void setContinueAfterError(boolean continueAfterError) {
     public boolean isContinueAfterError() {
         return continueAfterError;
     }
+
+    @Override
+    public boolean isAuthRequired() {
+        return false;
+    }
 }

zanata-client-commands/src/main/java/org/zanata/client/commands/stats/GetStatisticsOptionsImpl.java

@@ -112,4 +112,9 @@ public String getCommandName() {
     public String getCommandDescription() {
         return "Displays translation statistics for a Zanata project version.";
     }
+
+    @Override
+    public boolean isAuthRequired() {
+        return false;
+    }
 }