Seperate persons construction and households construction into two modules

[wniroshan]

Currently, all the persons and households are generated in a single run. This needs to be separated such that persons construction and household construction can be run independently. The program will read in a parameter specifying whether it should only produce persons distribution or full households distribution.

The outcomes of this change are as follows:

• If persons population needs to be generated independent of households, it can be achieved by running the persons construction module. In this case households file will not be generated and the only output is the list of persons in the given area in csv format.
• When households need to be generated both modules will be executed. The output will contain:
  1. All the persons, families and households in 3 separate csv files. The correspondences between entities in 3 files are maintained with IDs.
  2. A json file with addresses and households living these addresses. The addresses in the json file contain the ID of the household living in them.

[wniroshan]

Fixed in 430b711. Specify "-p" flag to only construct persons