Introduced VistaDB dialect

Also tests copy-pasted from SqlServer ones
Made some tests pass
Made all SqlServer tests pass for VistaDb4
Merge remote-tracking branch 'upstream/master'
Made VistaDB provider build
VistaDB4 provider cloned to VistaDB5 provider

Also added separate tests project
VDB5 provider optimized to use new dbms features
Default extension for VistaDB5 provider is vdb5
Update VistaDB4Expression.cs

Fixed expression parsing for Equals method on column (argument formatting and null check were missed).
Update VistaDB5Expression.cs

Fixed expression parsing for Equals method on column (argument formatting and null checking were missed).
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/ilyalukyanov/ServiceStack.OrmLite
Fix insert/update of Nullable DateTimeOffset in POCO
Merge pull request #389 from tvjames/nullable-datetimeoffset-poco

Fix insert/update of Nullable DateTimeOffset in POCO
Fix RowVersion for SqlServer
Make JoinSqlBuilderTest safe for all db providers
remove deprecated access to LimitExpression
re-factor SqlExpression sql generation into DialectProvider
Refactor JoinSqlBuilder to use new DialectProvider SqlExpression support
Add SqlExpressionTests