Only use ColorMapper if jAnsi is present, ignore it if not

This change allows slf4bukkit to run on Bukkit implementations without jansi by making ColorMapper an interface. Instances are created by using a ColorMappingFactory: If the Bukkit implementation bundles jAnsi, an AnsiColorMapper is returned that maps ChatColors to their ansi equivalents; if the Bukkit implementation does not bundle jAnsi, a NotSupportedColorMapper is returned that returns strings as is.

src/main/java/org/slf4j/impl/BukkitLoggerAdapter.java

@@ -45,6 +45,7 @@
 package org.slf4j.impl;
 
 import info.ronjenkins.slf4bukkit.ColorMapper;
+import info.ronjenkins.slf4bukkit.ColorMapperFactory;
 import info.ronjenkins.slf4bukkit.ColorMarker;
 
 import java.io.IOException;
@@ -218,6 +219,7 @@ public final class BukkitLoggerAdapter implements Logger {
   // The logger name.
   private final String                         name;
   // The short name of this simple log instance
+  private final ColorMapper                    mapper                              = ColorMapperFactory.create();
   private transient String                     shortLogName                        = null;
 
   // NOTE: BukkitPluginLoggerAdapter constructor should have only package access
@@ -1043,6 +1045,6 @@ public final class BukkitLoggerAdapter implements Logger {
 
     // Log the message.
     logger.log(BukkitLoggerAdapter.slf4jLevelIntToBukkitJULLevel(level),
-               ColorMapper.map(buf.toString()));
+               mapper.map(buf.toString()));
   }
 }