Add a script for generating hansard statistics for Jessica

Fixes #1160.  This was a one-off request, but probably worth
committing to the repository in case we need to regenerate these
in the future.  This is a very slow and inefficient script - however,
this seems like a case where trading off speed of development against
speed of execution is reasonable.
The Women's representatives are Members of the National Assembly

... so don't count them separately, even though their association
with places is different from constituency members of the NA.
Output a per-speaker spreadsheet too, as requested by Paul and Jessica

For the per-speaker spreadsheet, this just picks a day in the
middle of the date range to find positions for - it would be better
to consider overlaps between the whole date range and positions.
Merge branch 'feature/kenya-hansard-statistics'