References clean up

Removed unused references from
- Cassandra.DSE.csproj
- Cassandra.IntegrationTests.csproj
- Cassandra.Tests.csproj

Projects compile, unit tests pass
Tests clean up

- Added license header to the test files that were missing it
- Removed unused namespaces
- Moved ThreadPerTaskScheduler from Cassandra to Cassandra.Tests
Input validation

Checking parameter for null
Unit test coverage

- AbstractResponse (4 tests added)
- ResponseFrame ( 2 tests added)
Add failing tests for Linq First and FirstOrDefault CSHARP-162
Fix CqlQuerySingleElement.Execute method CSHARP-162
Tests Linq: Count, Take and OrderBy integration tests
Check that PreserveStackTrace method exists on the current platform.

- Ignore MemberAccess permission exception.
- Add 2 test for exceptions on partial trust and stack trace.
Tests Linq: UpdateIf integration test
Version bump 2.1.1
Add or Update License Headers
CSHARP-165 Add an address translator
Linq: Use TaskHelper.WaitToComplete on sync executes CSHARP-167

- Add 4 integration tests
Version bump
Add linq support for counter

Add linq support for counter, value set in object is used for increment.
Add tests
Merge branch '2.1' of https://github.com/mfiguiere/csharp-driver into 2.1-license
Merge branch 'master' of https://github.com/dtretyakov/csharp-driver into translator

Conflicts:
	src/Cassandra/HostConnectionPool.cs
Minor test and tracing fixes for CSHARP-165
Merge branch 'AddLinqSupportForCounter' of https://github.com/Youscribe/csharp-driver
added params check