[REEF-1816] Upgrade nuget.exe to version 4.1. Latest version of nuget.exe is required in order download some recent packages such as the latest version of Newtonsoft.Json.
[REEF-1816] Upgrade nuget.exe to version 4.1.
Latest version of nuget.exe is required in order download some recent packages
such as the latest version of Newtonsoft.Json.

JIRA:
  [REEF-1816](https://issues.apache.org/jira/browse/REEF-1816)

Pull Request
  This closes #1319

jwang98052/incubator-reef,dongjoon-hyun/incubator-reef,dougmsft/reef,jwang98052/reef,dongjoon-hyun/incubator-reef,markusweimer/reef,markusweimer/incubator-reef,shravanmn/reef,dongjoon-hyun/reef,markusweimer/incubator-reef,shravanmn/reef,dongjoon-hyun/reef,jwang98052/incubator-reef,apache/incubator-reef,dongjoon-hyun/incubator-reef,shravanmn/reef,singlis/reef,markusweimer/incubator-reef,shravanmn/reef,apache/reef,jwang98052/reef,motus/reef,apache/reef,markusweimer/reef,singlis/reef,markusweimer/reef,singlis/reef,jwang98052/reef,apache/incubator-reef,markusweimer/reef,apache/reef,markusweimer/reef,shravanmn/reef,jwang98052/incubator-reef,dongjoon-hyun/incubator-reef,shravanmn/reef,dougmsft/reef,apache/reef,jwang98052/reef,singlis/reef,motus/reef,motus/reef,apache/incubator-reef,markusweimer/reef,apache/incubator-reef,markusweimer/incubator-reef,motus/reef,dougmsft/reef,apache/reef,apache/incubator-reef,jwang98052/incubator-reef,motus/reef,dongjoon-hyun/incubator-reef,dougmsft/reef,dongjoon-hyun/reef,dongjoon-hyun/reef,dongjoon-hyun/incubator-reef,apache/incubator-reef,apache/reef,dongjoon-hyun/reef,dougmsft/reef,jwang98052/incubator-reef,jwang98052/reef,singlis/reef,apache/incubator-reef,dougmsft/reef,apache/reef,dongjoon-hyun/reef,jwang98052/incubator-reef,jwang98052/reef,jwang98052/reef,dougmsft/reef,dongjoon-hyun/incubator-reef,markusweimer/incubator-reef,shravanmn/reef,motus/reef,markusweimer/incubator-reef,markusweimer/reef,singlis/reef,singlis/reef,jwang98052/incubator-reef,motus/reef,dongjoon-hyun/reef,markusweimer/incubator-reef