Mandatory CHANGELOG.rst

[jayvdb]

This repo has a template for CHANGELOG.rst, but setup.py.jj2 should be usable without a CHANGELOG.rst.

I have repos without any history-like file, and others using different filenames. It is quite common for projects to use a variety of solutions for changelogs, and they may not want to have a redundant CHANGELOG.rst just to make use of this setup.py.jj2 template.

I think the neatest easy solution is improve setup.py so that existence of CHANGELOG.rst is checked at runtime, and ignored if not present.

Then setup.py.jj2 can be more used now by people with other solutions for CHANGELOG, and more complicated or alternative solutions for CHANGELOG can then be added if people want to.

[jayvdb]

templates/MANIFEST.in.jj2 also expects a CHANGELOG.rst

[chfw]

MANIFEST.in.jj2 is a bit hard to include a condition. let me invent something.

[jayvdb]

Ya, separate issue regarding MANIFEST.in.jj2 : #16

[chfw]

fixed by 2c73a42