Remove uneeded references & fixed typo in string.
Updated README.md to point to branch for pre EF6 version.
Added failing test for issue #33
Fixed issue #33
Merge pull request #38 from andypelzer/issue33

Fix for issue #33
Added failing test and fix for nullable key properties that are mapped to non-nullable columns. Fixes #22.
Merge pull request #40 from andypelzer/issue22

Fix for issue #22