Create "chrome31" branch and an archive 31.2 release before updating to a newer CEF

[GoogleCodeExporter]

Create the branch only after CEF 1 code path was removed (Issue 106). Make sure
there are no CEF 1 binaries left. Also make sure that there aren't any CEF 3
binary files. The var/ directory is 1.21 MB, maybe remove some files from there.

• Blocked on: Restructure directories (binaries, installer, libraries) to allow for git branching #178

[cztomczak]

Removing CEF 1 code path might break things, so leaving as is. CEF 1 binaries removed (Issue #103). An archive 31.2 release is ready: https://github.com/cztomczak/cefpython/releases/tag/v31.2 .

New branch "cefpython31" created. This branch still contains some useful CEF Python 1 code that wasn't yet ported to CEF Python 3, so keep it in archive, as it contains:

• panda3d example
• http authentication dialog default implentation on Windows; a php example http_authentication.php