Add Address Space Hierarchy endpoint

[dmbokhan]

No description provided.

[jvoss]

Hi @dmbokhan, thank you for this PR! I was able to resolve the black linting issue but it looks like some tests still need to be flushed out to provide coverage:

Run coverage report -m --fail-under=100
Name                                   Stmts   Miss  Cover   Missing
--------------------------------------------------------------------
prsw/__init__.py                           2      0   100%
prsw/api.py                               34      0   100%
prsw/exceptions.py                         3      0   100%
prsw/ripe_stat.py                         63      1    98%   95
prsw/stat/__init__.py                      0      0   100%
prsw/stat/abuse_contact_finder.py         35      0   100%
prsw/stat/address_space_hierarchy.py      30      2    93%   53, 121
prsw/stat/announced_prefixes.py           59      0   100%
prsw/stat/asn_neighbours.py               66      0   100%
prsw/stat/looking_glass.py                58      0   100%
prsw/stat/network_info.py                 17      0   100%
prsw/stat/ris_peers.py                    43      0   100%
prsw/stat/routing_history.py              79      0   100%
prsw/stat/rpki_validation_status.py       35      0   100%
prsw/stat/whats_my_ip.py                  12      0   100%
prsw/validators.py                        29      0   100%
--------------------------------------------------------------------
TOTAL                                    565      3    99%
Coverage failure: total of 99 is less than fail-under=100

[coveralls]

coverage: 100.0%. remained the same
when pulling d4859f7 on dmbokhan:master
into 9cc8d09 on jvoss:master.