Exclude gems {ext,spec,test,vendor} from generated package
Summary
We shouldn't need to ship C-source, vendored code, and tests of gem distributions
Proposal
Gems with native code are leaving both the native code, the intermediate object files, and the final .so in the gem tree. We should only need the .so files, and ruby lib trees, so exclude the rest.
Estimated wins are somewhere around 180Mb
References
#1778 (comment 61039313) #1778 (comment 61039797) #1643 (closed)