Remove JANSI dependency in 2.x (#3070)

This commit:

- Removes support for the outdated [Jansi 1.x](http://fusesource.github.io/jansi/) version in `Console` appender.
- Rewrites `JAnsiTextRenderer`, use in the `%m{ansi}` and `%ex{ansi}` pattern converters to use our internal ANSI support instead of Jansi.

Fixes #1736.

Author: ppkarwasz

log4j-1.2-api/src/test/java/org/apache/log4j/config/AbstractLog4j1ConfigurationTest.java

@@ -242,13 +242,6 @@
       <scope>test</scope>
     </dependency>
 
-    <!-- Required for console color support in Windows -->
-    <dependency>
-      <groupId>org.fusesource.jansi</groupId>
-      <artifactId>jansi</artifactId>
-      <scope>test</scope>
-    </dependency>
-
     <!-- Used for JMS appenders (needs an implementation of course) -->
     <dependency>
       <groupId>javax.jms</groupId>