Maintain order of original data

[jpmckinney]

closes #8

I'm not sure what the function of the sorted is. If it serves a function, there should be a test that fails without it.

[kindly]

@jpmckinney
This is very tricky to test as python dictionaries are inherently not ordered so it could pass sometimes and fail others for the same test. I have had tests that fail about 1 in 10 times or some people and not because of random dictionary ordering.
The aim of the sort was to make sure longer paths come after shorter ones otherwise the unflattering will not work.

However, to make sure this is correct we should add OrderedDicts instead of plain dictionaries in these places:

https://github.com/open-contracting/ocds-merge/blob/master/ocdsmerge/merge.py#L170
https://github.com/open-contracting/ocds-merge/blob/master/ocdsmerge/merge.py#L199

then we definitely do not have to worry about the sorting and it will keep order.

[jpmckinney]

I've updated those two lines now.