Fix "Map" block type and add basic tests for Hero and Map types (#19)
* Moved Map and Slideshow logic out of df_tools_blocks.
* Add basic tests for the Hero and Map block types.
* Added simple proximity pseudo-field for all Entity types.
* Moved block tests to dfs_dev, which enables required modules.
* Added all block-providing df_tools submodules as dependencies to df_tools.info.yml.