Java garbage collection bugfix

This pull request adds an arraylist of type Buffer to
the Request class.  Whenever a request object is created
that has associated buffers, the buffers should be added
to this array list so the java garbage collector does
not dispose of the buffers prematurely.

This is a more robust expansion on the idea first proposed by
@ggouaillardet

Fixes #369

Signed-off-by: Nathaniel Graham <[email protected]>

Author: Nathaniel Graham