This eliminates the dual solutions and brings Contrib into the
project.json fold.
- Tests are ported to xUnit though SQLite is disabled on DNX due to
Issue #375 (Interop loads fail in the VS runner and  params are busted
regardless).
- Projects are consolidated down to what's currently possible with
project.json.
- Contrib moved to: Dapper.Contrib and Dapper.Tests.Contrib (so tests
appear at the end, no other reason vs. Dapper.Contrib.Tests)
- EF moved to: Dapper.EntityFramework(.StrongName)
- Rainbow moved to: Dapper.Rainbow
- SqlBuilder moved to: Dapper.SqlBuilder
- Packages are removed since it's not current-tooling friendly to keep
them (nor was it using them).
- xUnit implemented in Contrib via abstracts - this allow us to very
quickly add any database provider to the rig in a very concise way.
- Contrib unit tests fixed in various places - they were not
parallel-runner friendly
- Nuspecs removed, since they aren't used anymore (to eliminate
confusion)
- Removed speed tests for libraries that aren't on current versions of
.Net (what would we be comparing?)
- Perf tests moved to Dapper.Tests (consolidation from
Dapper.DNX.Tests), but aren't activated yet (no define)