Only process files with .conf extensions in conf.d directories

load_config_dir and load_module_dir will now only process files with names
ending in .conf, preventing automatically generated backup files (like those
created when upgrading via dpkg, or editing in some editors) from being
processed.
New asynchronous http::Session locking in sconesite

Remove code which spins waiting to lock sessions, as this can cause the whole
server to lockup if all threads get into this state. Sessions are now only
locked when required (i.e. before processing in sconesite), and this is done
asynchronously, returning from evemt processing if the session cannot be locked
and retrying later.
Fix mismatched new[] and delete[]
Don't run tests for maths module if not built
Update debian/changelog for 0.9.8ppa7