Fix unittests and more pep8 conforming

- In our unittest we defined 'is_installed' to be a bool when in fact we wanted
    to verify if a package is installed via the _method_ is is_installed. Since
    overriding that method with our variable definition we basically removed
    any functionality of 'is_installed' method in Plugin class.
  - Initializing a fake plugin to test was failing due to our global
    logger not being initialized. Put a simple check in the library to
    make sure the logger is defined no matter what the calling state does.
  - Make import selinux conditional
  - Add travis-ci support
  - Rename README to utilize travis-ci build status and other markdown supported
    features

Signed-off-by: Adam Stokes <adam.stokes@ubuntu.com>