Clone build/gh-pages as a shared repository.

build/gh-pages is a temporary repository and can be well
cloned using a reference to the project repo.
Fix invalid syntax and refine from nonzero ADP.
Strip dG values so both datasets have no ESDs.

Having ESDs present for only X-ray dataset gave it much
larger weight to chi2 than the neutron one, although their
amplitudes were comparable.

Add a copy of x-ray data with ESD columns removed.
Fix ContributionResults.rw formula so it uses ESDs.

Also add cumchi2 and cumrw attributes to ContributionResults class
for cumulative arrays of chi2 and Rw.
Fix FitResults formula for combined rw.

Also add cumchi2 and cumrw attributes for cumulative of chi2 and Rw.
Use OrderedDict for FitResults contributions.

Contributions are ordered in FitRecipe so their corresponding
results should be ordered as well.
Show warning do not crash for missing version.cfg.

Also use RawConfigParser to avoid "%" interpolations.
Add fallback version.  Support commit metadata for git archive.

Switch to RawConfigParser to avoid issues with "%" interpolation.
Add commit metadata that expand for git tarball.
Improve resolution of version metadata.

Use gitarchive.cfg first, then git describe.
Do not export git-related files.