fixed small mistakes on the docs
Removed unneccesary PGThread.

Django connections are thread locals by default, it's safe to attach
attributes to the DatabaseWrapper, because those are thread safe.
Removed connection.get_schema() and connection.get_tenant() methods,
those were not very pythonic at all. Use connection.schema_name and
connection.tenant properties instead.
Merge branch 'master' of github.com:bernardopires/django-tenant-schemas
Resolved merge conflicts on docs regarding tenant and schema_name
readded backwards compatibility (get_schema_name and get_tenant)
fixed get_schema_name not being called get_schema