minor modifications

Added mini joran tutorial/introduction

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- updated javadoc accordingly

- minor fix on SMTPAppender javadoc

- removed PostContentConverter from PatternLayout.

- moved CyclicBuffer.java to the core module
- modified classic module's SMTPAppender accordingly

- modified the behaviour of postCompileProcessing() accordingly

- LogbackValve now implements the Contained interface from tomcat

- added a RequestParameterConverter, that works just like the RequestAttributeConverter except for one small obvious detail
- added several patterns to PatternLayout

- added a TomcatServerAdapter
- organized imports in RequestLogImpl.java and JettyBasicTest.java.

- corrected basic test, it now creates the POST request correctly and retrieves the post content, too.

- AccessEvent now remembers if the postContent has already been accessed
- updated tests

- added a PostContentConverter
- created a test case and test setup to create and launch a Jetty server
- added a getPostContent method to AccessEvent
- added the corresponding pattern to PatternLayout
- added javadoc to RequestLogImpl

- Moved classes to Core module when possible.

- Moved classes to Core module when possible.

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- corrected hsqldb.sql and mysql.sql
- added a testcase that creates an HSQLDB server, with a test database and uses it to test DBAppender.
- modified some javadoc

- modified ignore list on examples/classes/

- added a chapter4 package in the examples, containing several configuration files for logback, as well as
a ConfigurationTester class to launch logback with a specified config. file.

- updated RollingFileAppender.java and FixedWindowRollingPolicy.java to show a link to the faq when adding errors to the context

- updated site.xml to use the new version of logback-skin
- updated shortIntro.xml