*: bump etcd/client and grpc version

[xiang90]

for #3772

[xiang90]

@jefferai

hmm... is there something wrong with the current CI? it seems this PR is blocking forever :P.

[benpaxton-hf]

@xiang90 looks like Travis is having issues: https://www.traviscistatus.com/

[jefferai]

@xiang90 I'm going to have to schedule this for 0.9.3 -- 0.9.2 is going out very soon and since we use grpc heavily I'm wary of merging updates to it without us having the opportunity to do due diligence.

[xiang90]

@jefferai

ok. that is even better. thanks.

[xiang90]

@jefferai

the stable gRPC go version we are aware of is 1.7.5.

[raoofm]

@xiang90 grpc go is v1.9.1 now

[jefferai]

Deps have been bumped.