Do not import * in lib.exaproxy.util.interfaces

Wildcard imports should be avoided for many reasons, such as making code
checkers such as pyflakes work.

Also see:
https://docs.python.org/2/tutorial/modules.html#importing-from-a-package
Merge pull request #26 from ema/master

Do not import * in lib.exaproxy.util.interfaces
silently close on KeyboardInterrupt
Merge branch 'master' of https://github.com/Exa-Networks/exaproxy