Vendor Thrift code

[yurishkuro]

Which problem is this PR solving?

Thrift 0.11 has backwards incompatible changes, which prevents go get install. Granted, that method of dependency management is discouraged anyway. In any case, whichever version of thrift we pick we will cause incompatibilities for some applications.

Resolves #184

Short description of the changes

The portion of Apache Thrift library is copied into thrift directory as vendored code.

[codecov]

Codecov Report

Merging #303 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #303   +/-   ##
=======================================
  Coverage   86.79%   86.79%           
=======================================
  Files          54       54           
  Lines        2954     2954           
=======================================
  Hits         2564     2564           
  Misses        275      275           
  Partials      115      115

Impacted Files	Coverage Δ
testutils/udp_transport.go	58.06% <ø> (ø)	⬆️
transport/http.go	81.66% <ø> (ø)	⬆️
transport/zipkin/http.go	75.43% <ø> (ø)	⬆️
transport_udp.go	92.59% <ø> (ø)	⬆️
utils/udp_client.go	0% <ø> (ø)	⬆️
testutils/mock_agent.go	81.92% <ø> (ø)	⬆️

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[black-adder]

Well I guess that's one way to do it

[vprithvi]

I think we should have something equivalent to maven's enforcer plugin to ensure that this dependency isn't accidentally reintroduced transitively.

Maybe adding a grep for the thrift library in gopkg.lock, and glide.lock and making the build pass based on the result could achieve this.