Esky

* Compatability fixes for Win64; thanks Robin Dunn.
* Edge-cases fixes in DefaultVersionFinder; thanks fingul.

* Many small fixes for Mac OSX, including compatibility with newer
versions of py2app; thanks thomasschaff, poupas, and others.
* Fix various unicode-handling issues on Python3; thank vkosh.
* Use a timeout in calls to urlopen(); thanks kollivier.
* Updates and improvements to tutorial code; thanks thomaschaaf, komola.

* Avoid a possible infinite loop during updates; thanks vkosh.

* Fix downloading of updates when there was a HTTP redirect encountered
as part of VersionFinder.find_versions().
* Fix win32 bootstrap version of abspath() to correctly handle UNC paths.

* Fix some env-var-handling errors on OSX; thanks Robin Dunn.
* When using a custom win32 chainloader, be less aggressive about
changing the current working directory on startup.
* Clean up handling of unbuffered mode in py2exe. (The old code
never actually worked; the new code works most of the time but
might give you the wrong mode if running from a partial update)
* esky.sudo: avoid deadlocking if the helper process dies.

* Added esky.util.appexe_from_executable, a convenience method to
find the bootstrapping exe corresponding to the running program.
* Use "bsdiff4" module in preference to cx-bdiff if available; it's
got a simpler API and is pip-installable.
* Update rpython-compilation support for PyPy v1.5.
* Better handling of non-alpha chars in app names; thanks Rafe Kettler.
* py2exe: support the skip_archive option; thanks yflau.