Key Data Type other than int and writable key (e.g. Guid)

- IsKeyWriteable to return default value
- Insert<T,TKey> method
- ISqlAdapter.Insert<TKey> returns TKey
- SqlServerAdapter.Insert<TKey> (Set Key value only if writeable)
- PostgressAdapter.Insert<TKey> (Set Key value only if writeable)
- Updated KeyAttribute to support AllowWrite property
Updated Tests For Key Data Type other than int (e.g. Guid)

- Created RunTestsGeneric
- Setup adds two tables Persons and Managers
Updated Tests For Key Data Type other than int (e.g. Guid)

- Added TestsGeneric.cs 
- <Compile Include="TestsGeneric.cs" />
Updated Tests For Key Data Type other than int (e.g. Guid)

- Tests with Int64/Long as BigInt with Identity(0,0) in SqlCE.
- Tests with Guid as UniqueIdentifier in SqlCE with Key created in Code.
Merge branch 'master' of https://github.com/jd4u/dapper-dot-net into dev

Conflicts:
	Dapper.Contrib/SqlMapperExtensions.cs

Key Data Type other than int and writable key (e.g. Guid, varchar)