added NuGet 2.6
added NuGet 2.6

stormleoxia/teamcity-nuget-support,JetBrains/teamcity-nuget-support,JetBrains/teamcity-nuget-support,stormleoxia/teamcity-nuget-support,JetBrains/teamcity-nuget-support,stormleoxia/teamcity-nuget-support,JetBrains/teamcity-nuget-support