read readme from the elasticmock package file.

[infinite-Joy]

This issue shows when trying to pip installing from the wheel file.

The following PR should fix this issue.

[coveralls]

Coverage increased (+0.6%) to 98.83% when pulling f8cf93c on infinite-Joy:bug18.missingreadme into 57f004b on vrcmarcos:master.

[tdhopper]

Collecting elasticmock
  Downloading https://files.pythonhosted.org/packages/ee/27/d70e1ca53b8080138f613e4d600831397acd6bf7fdc466bea32692fc9bf5/ElasticMock-1.3.5.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/var/folders/mg/9dh5w1r93w3630s4p0y33_c40000gn/T/pip-install-8jE_6k/elasticmock/setup.py", line 10, in <module>
        with open(path.join(this_directory, 'README.md'), 'r') as f:
    IOError: [Errno 2] No such file or directory: '/private/var/folders/mg/9dh5w1r93w3630s4p0y33_c40000gn/T/pip-install-8jE_6k/elasticmock/README.md'```