TODO for mod_jserv:

- Currently the server loops continuously if it can't start the Java VM:
  for example, if the mod_jserv class files are missing.  Instead of this,
  we should disable jserv.  However, we do want the server to restart the
  JVM if it just happens to be killed.

- Implement correct behavior when exception UnavailableException is thrown 
  from a servlet.

- Implement correct behavior when servicing servlet that implements 
  SingleThreadModel

- All messages logged after the headers are sent, will only be log with
  the next request to the servlet. (AJPv2 protocol will address this.)

- Find a way to callback apache to handle things like filename/mime-type
  mapping and file path resolution. (AJPv2 protocol will address this.)
 
- Improve timeout control on servlet methods to prevent deadlocking JServ. 
  For example, if a servlet deadlocks, JServ won't be able to restart and most
  request to the servlet will never be able to complete.

- Implement a thread pool to lower the thread creation/starting overhead.

- Improve performance.

- We need a configurable servlet security sandbox (SecurityManager).  Some
  ideas are available at
     http://www.employees.org/~ikluft/apache/jserv_secmgr.html

- Servlet chaining: taking the output of one servlet (headers and content)
  and turning it into the input of another.  On other servlet runners, this
  can be triggered by the output's MIME type or as a chain specified prior
  to servlet invocation.

- Give ServletClassPath the ability to take relative paths to the Apache root
