Previously an addAfterCommitHook was used, but this is not run on transaction
aborts.  Now a Synchronizer is used which unconditionally closes the request
after a transaction is finished.

Not closing the request seems to have caused the database connections to be
kept open and these nasty log messages:

    CRITICAL ZODB.DB DB.open() has 42 open connections with a pool_size of 7

42 being the wrong answer in this case.

Make Yvo happy and keep testing our factored out distributions, so CMF doesn't have to grow a KGS of its own

line by default to avoid causing problems for proxy servers which do not
correctly handle multi-line headers. (Merged from 2.13 branch.)

The getaddrinfo API provides a superset of the info provided by gethostbyname but isn't ipv4 specific.

- related cleanup

- removed redundant Globals.DevelopmentMode initializations (setConfiguration is responsible for this)

- updated docs