Default PK Name for SQL SERVER

First commit: I added following pattern PK_{TABLE_NAME}_{ColumnName} for the name of the primary key for SQL SERVER.

Second commit:
I added PrimaryKeyName attribute which allows user specify custom name of the primary key. That name may contains two format items: {0} - table name {1} - column name. This attribute is only supported in Sql Server.

Commits connected with Issue #229