Remove JANSI dependency in 2.x (apache#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- Removes support for the outdated [Jansi 1.x](http://fusesource.github.io/jansi/) version in `Console` appender.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 apache#1736.

Author: ppkarwasz

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

@@ -117,8 +117,8 @@ private Layout<?> testConsole(final String configResource) throws Exception {
         final String name = "Console";
         final ConsoleAppender appender = configuration.getAppender(name);
         assertNotNull(
-                appender, "Missing appender '" + name + "' in configuration " + configResource + " → " + configuration);
-        assertEquals(true, getFollowProperty(appender), "follow");
+                "Missing appender '" + name + "' in configuration " + configResource + " → " + configuration, appender);
+        assertTrue("follow", getFollowProperty(appender));
         assertEquals(Target.SYSTEM_ERR, appender.getTarget());
         //
         final LoggerConfig loggerConfig = configuration.getLoggerConfig("com.example.foo");