Operations: port over HGRC files from main repo to share

Closes #324

The specific repo configuration was ignored in all Mercurial
operations initiated by the Rails app.

I've considered making links instead of copying the file, but
it could give rise to funny situations if the original HGRC
files get changed in concurrency with some operation.

Edition of the HGRC files is by no means atomic in itself,
but that's a separate issue. On the other hand, operations can be
arbitrary long, involving several calls to the `hg` executable.
One would not want the rules to change in the middle of that.
1 job for branch/heptapod