Release 1.1.12

[kwlzn]

docket:

• Don't ignore exit codes when using setuptools entry points #280 to resolve pex -c incorrectly alters exit codes #137
• Normalize and edify subprocess execution. #255
• Fix bdist_pex interpreter cache directory #286

[kwlzn]

planning to cut this as soon as the travisCI load dies down.

[kwlzn]

this is out: https://pypi.python.org/pypi/pex/1.1.12