[Axis2] Trace

[Samisa Abeysinghe]

I have added a trace method to log. Trace can be enabled with 
-DAXIS2_TRACE at compile time. If the macro is not defined, then trace 
would not be compiled into the code.

We can use this to help with entry exit tracing, that could be useful to 
trac execution paths when debugging.

Thanks,
Samisa...