CommandInfoTest: workaround for strange javac bug

Without this change, some javac versions fail with:

    [ERROR]
    /data/devel/jenkins-maven/workspace/SciJava-common/src/test/java/org/scijava/command/CommandInfoTest.java:[97,10]
    cannot find symbol
      symbol:   class Plugin
      location: class org.scijava.command.CommandInfoTest
    [INFO] 1 error

Notably, compilation fails on Ubuntu 12.04.5 LTS using:

    openjdk version "1.8.0_111"
    OpenJDK Runtime Environment (build 1.8.0_111-8u111-b14-3~12.04-b14)
    OpenJDK 64-Bit Server VM (build 25.111-b14, mixed mode)

But works fine on macOS Sierra using:

    java version "1.8.0_112"
    Java(TM) SE Runtime Environment (build 1.8.0_112-b16)
    Java HotSpot(TM) 64-Bit Server VM (build 25.112-b16, mixed mode)

Author: ctrueden

src/test/java/org/scijava/command/CommandInfoTest.java

@@ -94,7 +94,7 @@ public void testEnumParam() {
 	// -- Helper classes --
 
 	/** A command with an enum parameter. */
-	@Plugin(type = Command.class)
+	@org.scijava.plugin.Plugin(type = Command.class)
 	public static class CommandWithEnumParam implements Command {
 
 		public enum Choice {