Enable socket_timeout on unix_socket

[ryerh]

The timeout param for rpc.make_client only works when user provides host:port, but ignored when user provides unix_socket.

This PR fixed it.

Could you bump a new version as soon as this PR is accepted? pls.

[codecov]

Codecov Report

Merging #83 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master      #83   +/-   ##
=======================================
  Coverage   80.79%   80.79%           
=======================================
  Files          35       35           
  Lines        3540     3540           
=======================================
  Hits         2860     2860           
  Misses        680      680

Impacted Files	Coverage Δ
thriftpy2/rpc.py	81.69% <0%> (ø)	⬆️

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[ethe]

LGTM, thank you!