bulk_create sets primary keys on created objects

Addresses #19527
Changes to make django create a schema if one is specified in DjangoTestSuiteRunner.setup_databases
Fix injection of psycopg2 schema_path options

I was injecting multiple times the schema_path option, as I was assuming
that that part of the codepath would not be reentered after startup.
I was wrong, and this was causing the SSL handshake to mess up.
Modify "delete test database" confirmation to flush on subprocess pass-thru

When using django's testing framework with subprocess,
the prompt to confirm that the testing database was not printing
properly due to buffering. This explicitly flushes the buffer, which
is required for something interactive like this.
Fixup AliasedDatabaseTest related problems in setup_databases

AliasedDatabaseTest is newly introduced in 1.5.2.
It uses a dummy DB backend instead of the usual means of create_database,
and thus was having trouble with the schema injection we use for our
postgres-backed tests. This commit simply falls back to the original
argspec in that case