* Change to GetAll to allow the usage of a nullable type in T when T is an interface.

* Change to GetAll to allow the usage of a nullable type in T when T is an interface: further change to check if val == null and if so then don't try to assign it as a property value.

* Change to Get to allow the usage of a nullable type in T when T is an interface. (effectively the same change as the previous change to GetAll.)

* Change to GetAsync and GetAllAsync to allow the usage of a nullable type in T when T is  an interface.

* Added in UserWithNullableDob and IUserWithNullableDob.

Added in tests for GetAndGetAllWithNullableValues and  GetAsyncAndGetAllAsyncWithNullableValues.

* Added in .ConfigureAwait(false) in the GetAsync Test.
Added comment to identify which issue the test relates to.

* Added NullableDates tables to the test databases.
Adjusted variable names in GetAndGetAllWithNullableValues and GetAsyncAndGetAllAsyncWithNullableValues.

* Changed IUserWithNullableDob to INullableDate.

This brings behavior QueryAsync behavior on par with Query (sync) and properly returns nothing when an empty result set is encountered.

* fix equal tests

* fix test

* when inserting check if type implements IEnumerable<T> to determine if it's a collection
* when inserting, check if type is a collection by comparing its implemented interfaces to unbound generic type IEnumerable<> instead of the name "IEnumerable`1"

Combined 2 tests into one

This shows the importance of using DbType.DateTime2 in Dynamic Parameters to avoid precision truncation

Add literal replacement example to readme

Adding a dapper specific feed, for much easier pushing to NuGet. When
they implement Ctrl+Click in the UI this won't be necessary...or we
break down and automate it finally. Depends on signing plans later.

Removes NuGet workaround for pre-2.0 and lines up with other script
enhancements since.

Micro optimizations for CreateParamInfoGenerator

AddDynamicParameters repeated should work  while paramtype is DbString 

Netstandard2.0 Followup Cleanup

.NET Standard 2.0, for great justice.

This change:
- Removes the Assert shim
- Uses recommended xUnit methods (improving fail errors)
- Cleans up exception tests
- General test formatting fixes
- Removes the netcoerapp1.0 only testing (oops commit)

New overload so this isn't a breaking change. We can collapse down in v2.0 (including the Impl method).

Add dynamic overloads for:
- QueryFirstAsync
- QueryFirstOrDefaultAsync
- QuerySingleAsync
- QuerySingleOrDefaultAsync

This may change a lot in 2.x, but many people asking for them now so here they are. Unit tests also fixed for QuerySingleOrDefaultAsync.

Note: this builds on the netstandard2 branch because of the xUnit changes to go with VS 2017 15.3.

.NET Core 2 SDK is on the base Appveyor image now