Some improvements to the Common library
Implemented the EF6 Repository

Related Work Items: #116, #117, #118, #119
Added DbContextRepositoryBase

Related Work Items: #119
Refactored Arragro.Common.Tests and split out common test objects.
Added EF6 Integration Use Cases and Tests

Related Work Items: #120
Configured build for Arragro.EF6
Included build template
Fixed typo in nuspec
Fixed nuspec file
Reorganised folder structure