It should be possible to set a default attribute on the database level, specified with a custom attribute.

The attribute should be named "SqlDefaultValueAttribute" and take a string representing the SQL statement.

1. Create a new Attribute "SqlDefaultValueAttribute" in "SQLite.CodeFirst/Public/Attributes". The attribute should take a string in the ctor and initialize a property, named "DefaultValue"
2. Create a new ColumnConstraint "DefaultValueConstraint" in "SQLite.CodeFirst/Internal/Statement/ColumnConstraint" (Cover this with a Unit Test)
3. Extend the ColumnStatementCollectionBuilder to support the "SqlDefaultValueAttribute" and add the corresponding constraint
4. Extend the sample code to use the "SqlDefaultValueAttribute"
5. Extend the integration test SqlGenerationTest.cs