Added 'throws' clauses to Java method signatures for all wrapped
functions except getters.  refs #1011
Fix handle sweep code: make sure we're closing the right data handle, check the reference count before freeing, and use atomic increment to match the (unlocked) atomic decrement on close.

refs #844
Don't worry about handles that are referenced during connection close.

refds #844
Merge pull request #1015 from wiredtiger/java-exception

Updated java exception clauses