Switch to using a varargs syntax in CommandRunner.

Summary:
We use the array syntax for the final argument for CommandRunner.runCommand.
If we use the varargs syntax, calling the method becomes cleaner.

Test Plan: buck test --all
diff --git a/src/com/facebook/buck/cli/AbstractCommandRunner.java b/src/com/facebook/buck/cli/AbstractCommandRunner.java
index 413d8a0..875979c 100644
--- a/src/com/facebook/buck/cli/AbstractCommandRunner.java
+++ b/src/com/facebook/buck/cli/AbstractCommandRunner.java
@@ -77,7 +77,7 @@
   }
 
   @Override
-  public final int runCommand(BuckConfig buckConfig, String[] args) throws IOException {
+  public final int runCommand(BuckConfig buckConfig, String... args) throws IOException {
     ParserAndOptions<T> parserAndOptions = createParser(buckConfig);
     T options = parserAndOptions.options;
     CmdLineParser parser = parserAndOptions.parser;
diff --git a/src/com/facebook/buck/cli/AuditCommandRunner.java b/src/com/facebook/buck/cli/AuditCommandRunner.java
index 065c69f..c92dadb 100644
--- a/src/com/facebook/buck/cli/AuditCommandRunner.java
+++ b/src/com/facebook/buck/cli/AuditCommandRunner.java
@@ -33,7 +33,7 @@
   }
 
   @Override
-  public int runCommand(BuckConfig buckConfig, String[] args) throws IOException {
+  public int runCommand(BuckConfig buckConfig, String... args) throws IOException {
     if (args.length == 0) {
       console.printBuildFailure("No audit command is given.");
       printUsage();
diff --git a/src/com/facebook/buck/cli/CommandRunner.java b/src/com/facebook/buck/cli/CommandRunner.java
index 181768f..126f7fa 100644
--- a/src/com/facebook/buck/cli/CommandRunner.java
+++ b/src/com/facebook/buck/cli/CommandRunner.java
@@ -24,6 +24,6 @@
    * @param args the arguments passed to the command, not including the command name
    * @return the appropriate exit code for the command
    */
-  public int runCommand(BuckConfig buckConfig, String[] args) throws IOException;
+  public int runCommand(BuckConfig buckConfig, String... args) throws IOException;
 
 }