Refactoring acd_by_tile functions for parallel

[Matthew-J-Payne]

The parallel python and shell functions written by @ireading-uol require that only config_path and tile are passed to acd_by_tile_raster and acd_by_tile_vectorisation. This commit hopefully fulfils the necessary function structure.

• [x] acd_integrated_raster now behaves differently depending on whether do_parallel is True.
  • [x] acd_by_tile_raster now takes just config_path and tile
• [x] acd_integrated_vectorisation now behaves differently depending on whether do_parallel is True.
  • [x] acd_by_tile_raster now takes just config_path and tile

Ancillary changes:

• [x] .gitignore uses GitHub python ignore template
• [x] added config_path_to_config_dict, does what it says on the tin
• [x] minor changes to README.md

[Matthew-J-Payne]

Addresses #61 . Will keep issue open until proven not broken.