MS-SQL fixes for: tests, system tables, & table parsing.

Fixes parsing of the table names for MS-SQL when using a sub-select
within the FROM clause
Sets the tablename owner for system tables to dbo
All tests now pass.
sqlserver adapter code cleanup + refactored (ArJdbc::) MsSQL -> MSSQL
Fixing substring issue that prevents detecting a query that contains *
[mssql] run more tests, change default constrain sql on 2005+ (closes #320)
remove a few quoting methods (implemented in Java) + some more cleanup
Conflicts:
	test/simple.rb
[MSSQL] fix table/column name quoting - do not quote if quoted already
Conflicts:
	test/mssql_test.rb
need test-unit-context gem for some new (shoulda copied) ms-sql tests
[mssql] get_primary_key hack only needed for 2000 - thus move from utils
+ support Model.table_name to be set quoted as well as unquoted
Conflicts:
	lib/arjdbc/mssql/limit_helpers.rb
	lib/arjdbc/mssql/utils.rb
more ms-sql adapter rerfactoring (table_name / quoting related) :
- make sure it's clear when table_name need to get un-quoted/qualified
- introduce Utils (with not-just a bunch of unquoting helper methods)
- explicit table_exists? since super might change
Conflicts:
	lib/arjdbc/mssql/limit_helpers.rb
	lib/arjdbc/mssql/utils.rb
	test/mssql_test.rb
[mssql] more quoting tests + table_exists? shall return a true/false
add as400 primary key support and re-add explain method
[oracle] fix #insert (broken since execute+to_sql refactoring) keeping binds
respect 30 max identifier length with default sequence names
[oracle] native database types ala oracle-enhanced adapter