Java binding: make it available to other swig java binding

* If more than one module is used and SWIG proxy classes need
constructing/using across modules, there is no other option than expose
the getCPtr() of AvTranscoder java binding to public.
* See this link: http://sourceforge.net/p/swig/mailman/swig-
devel/thread/4ED006FD.6020403@fultondesigns.co.uk/
Sconscript: update name of dll

<name>'-'<version>.dll
Java binding: add avExport.i

Contains swig specificities to make AvTranscoder's Java binding
available to other swig java binding.
Merge pull request #77 from cchampet/dev_java_binding_available_to_other_java_binding

Get java binding available to other java binding