Complete issue #10

- Refactor IAuthenticator to include Scheme property and rename AuthUserInfo to UserInfo

- Implement BasicAuthentication by using AuthenticationHeaderValue instead of using NetworkCredentials

- Add URIUtils.Combine() method to combine path to a given URI

- Add AuthTest.TestGetAuthenticationHeaderValue(),TestBasicAuthenticationSuccess(), and TestBasicAuthenticationWrongPassword()

- Add replicationAdminPort to local-test.properties and test.properties

- Add LiteTestCase.GetReplicationAdminPort()
or even just:
```csharp
new Uri(baseUri , path); 
```