Add :auto_increment key to schema information for primary key columns (Fixes #919)

This includes implementations for the most common adapters
(PostgreSQL, MSSQL, MySQL, JDBC).  It actually works on SQLite too,
though the test is skipped there, because all integer primary keys
are autoincrementing on SQLite.
Consider integer primary keys as incrementing on Oracle

Oracle uses triggers to pull values from sequences, and I don't
think it's possible to parse that information out.  Because Oracle
uses NUMBER instead of integer for columns, the default setting
of :auto_increment won't work.
Parse :auto_increment schema entry correctly on DB2
Skip autoincrementing primary key spec on fdbsql

fdbsql uses the information schema views for metadata, and they
don't contain whether the columns was a serial column or not.
So keep the default behavior of assuming integer primary keys
are auto incrementing, but skip the spec.
Don't assume composite integer primary keys are autoincrementing
Fix minor fallout from using :auto_increment in schema hashes
Use MSSQL-specific schema parsing instead of JDBC schema parsing with jdbc/sqlserver driver

This fixes the autoincrementing primary keys schema spec on
jdbc/sqlserver.  It used to be that the JDBC schema parser was
more robust, which is why it was preferred, but that is no longer
true, so switching to the MSSQL-specific schema parser is better.