TC3: remove core.Constants

[cm...@yahoo.com]

- SERVLET_NAME, SERVLET_VERSION belongs to corresponding facade ( tomcat
can support multiple versions ).

- JSP_NAME, JSP_VERSION belongs to jsp interceptor ( as the interceptor is
the only one to know what version it's integration ) or whatever class
knows about jasper

- DEFAULT_CHARSET belong to OutputBuffer or actual implementation. 

- TOMCAT_NAME and VERSION belong to ContextManager, the entry point and
controler of tomcat. 

As an extra benefit, each variable will be defined in the class where it
belongs ( no need to open another file ), and we'll have one less file ( 
we don't actualy need) in the core :-)

( the first 2 must be moved in order to support multiple facades and
versions, and keeping Constants just for TOMCAT_NAME/VERSION is too much )

Costin