[okfn-help] Converted various repositories from svn to hg

[Rufus Pollock]

Have now converted CKAN and Microfacts/Weaving History repositories
from svn to hg:

<https://knowledgeforge.net/ckan/hg>
<https://knowledgeforge.net/microfacts/hg>

In addition the datapkg, vdm (versioned domain model) and ckanclient
which were all in the ckan repository have been split out as separate
mercurial repositories:

<https://knowledgeforge.net/okfn/vdm/>
<https://knowledgeforge.net/ckan/datapkg/>
<https://knowledgeforge.net/ckan/ckanclient/>

In all cases the old subversion repository is now deprecated and
should not be used.

Rufus

PS: TODO: update this in relevant documentation and project pages on
okfn.org and wikis!