Drop Python 2.6 on appveyor, install 'grpcio' unconditionally.

[tseaver]

grpcio 0.14.0 installs without errors on Python 3.4+.

See #1863, failures after merging #1877.

[daspecster]

@tseaver, do you have appveyor hooked up to your github username? or if you want I can copy this branch to my repo and run it.

Update: Build running @ https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn

[tseaver]

Oops, I was out-of-sync and merged ahead of seeing your build finish.

[daspecster]

Np, I have it building master now https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn

[daspecster]

@tseaver lots of
ImportError: cannot import name timestamp_pb2
https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn/build/1.0.5.master/job/9yeww3g7vk6wvdcr#L543

[daspecster]

A little different for py3,
https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn/build/1.0.5.master/job/0dn0nee07e773mc4#L194

[tseaver]

Ugh. I'm not sure what to say: somebody has hosed the google namespace package.

[daspecster]

For windows specifically?

[daspecster]

It's still that unbuilt egg error for py3 https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn/build/1.0.5.master/job/0dn0nee07e773mc4#L149

And yeah for py2 it can't import timestamp_pb2 from google.protobuf.
https://ci.appveyor.com/project/daspecster/gcloud-python-pjqjn/build/1.0.5.master/job/f8l9c4aixytmd4m0#L551

[daspecster]

Could try and switching protobuf == 3.0.0b2 from 3.0.0b3?

[tseaver]

Maybe we should revert this PR (or at least the bit which globally installs grpcio) and just leave Appveyor borken until a fix is released for grpc/grpc#6939.

[daspecster]

Wouldn't we want it this way once grpc/grpc#6939 is resolved?