starting to make `RepeatedField` quack like an array

additional changes:
* make sure gemspec gets all ruby code files
* add homepage in gem spec removes one of the warnings, and the gem spec authors are pushing
everyone to include a homepage in the gem
* remove excess whitespace in test suite to bring formatting inline with the rest of the file

Change-Id: Idb29077c153530de78ce28c094442aa8f51ddd25

Change-Id: I33479e529b060e4fed532a827a386d3baecc835e

This update conforms to our two-numbers-after-alpha scheme that allows
us to bump the last number if we need to re-upload a gem. (Rubygems does
not allow re-use of a version number once a gem is uploaded.)

Change-Id: Ia8e7c129d19800afd66f8052785cf5a00462c7ba

- A golden-file test that ensures protoc produces known-valid output.
- A Ruby test that loads that golden file and ensures it actually works
  with the extension.

This split strategy allows us to test end-to-end without needing to
integrate the Ruby gem build system and the protoc build system. This is
desirable because we do not want a gem build/install to depend on
building protoc, and we do not want building protoc to depend on
building and testing the gem.

system. The Ruby module build now uses an amalgamated distribution of
upb, and successfully builds a Ruby gem called 'google-protobuf' with
module 'google/protobuf'.