Move client v1 api rest servlets into a "client/v1" directory

synapse/client/__init__.py

synapse/client/v1/__init__.py

synapse/client/v1/admin.py

synapse/client/v1/base.py

synapse/client/v1/directory.py

synapse/client/v1/events.py

synapse/client/v1/initial_sync.py

synapse/client/v1/login.py

synapse/client/v1/presence.py

synapse/client/v1/profile.py

synapse/client/v1/register.py

synapse/client/v1/room.py

synapse/client/v1/transactions.py

synapse/client/v1/voip.py

synapse/server.py

tests/client/__init__.py

tests/client/v1/__init__.py

tests/client/v1/test_events.py

tests/client/v1/test_presence.py

tests/client/v1/test_profile.py