PyPI installation is busted because CHANGLOG.md is not in the MANIFEST

```
Downloading/unpacking pydocx==0.3.15
  Running setup.py egg_info for package pydocx
    Traceback (most recent call last):
      File "<string>", line 14, in <module>
      File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 56, in <module>
        long_description=get_description(),
      File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 22, in get_description
        return get_file('README.rst') + get_file('CHANGELOG.md')
      File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 17, in get_file
        with open(rel_file(filename)) as f:
    IOError: [Errno 2] No such file or directory: '/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/CHANGELOG.md'
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):

  File "<string>", line 14, in <module>

  File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 56, in <module>

    long_description=get_description(),

  File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 22, in get_description

    return get_file('README.rst') + get_file('CHANGELOG.md')

  File "/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/setup.py", line 17, in get_file

    with open(rel_file(filename)) as f:

IOError: [Errno 2] No such file or directory: '/var/lib/jenkins/virtualenvs/pstat_ticket.b1DGHp/build/pydocx/CHANGELOG.md'
```