Avoid double quoting the schema names when used in PostgreSQL catalog
queries, where the identifiers are used as literal values and need to be
single-quoted.
Fix#476, again.
As shown in #476, it is sometimes needed to be able to quote the
identifier names even when loading from a file, that is when specifying
the target table name in the database uri.
To that ends, allow the option "identifier case" to be used in the file
based cases too. Fixes#476.
It's always been possible to set application_name to anything really,
making it easier to follow the PostgreSQL queries made by pgloader.
Force that setting to 'pgloader' by default.
Fix#387.
