Add CommannDefinition versions of Query(First,FirstOrDefault,Single,SingleOrDefault)Async and a few unit tests for them

Operate on db records instead of files.

Fix #573 - OrWhere yielding AndWhere statement

Remove a bunch of unnecessary (and *theoretically* dangerous, in a very unlikely scenario involving custom cultures installed on a box) C# 7 string $"...{...}..." usages

Fixed some syntax errors in project.json files

Add InListStringSplitCount; when set, causes `in @foo` parameters to be implemented using string_split

Test for #524 (believed to be a failing test; cannot validate or fix until I get the latest tooling installed)

Note: build.sh needs love from OS X/*nix later to match

This fixes null refs with the DNX MSBuild targets when building from
Visual Studio.

Related issue: #520

RC2 Upgrade!