This brings us more into line with other langauges, and makes it more
obvious when we are requiring protobuf generated code.

For JSON encoding we provide a new option to decide at
encode time whether to use camelCase or original proto field
names:

  json = MapMessage.encode_json(m, :preserve_proto_fieldnames => true)

More informative and more ruby-like

- Added RVM-based Ruby test driver that tests MRI and JRuby.
- Fixed JRuby compilation (at least in my current setup): force source
  version to 1.6 (Java 6) to allow generics and annotations.
- Modify the skipped JRuby JSON tests so that the exit code is 0 (skip()
  results in a failing exit code from `rake test`). An upcoming PR
  should fix JSON under JRuby in general soon.

* make consistent between mri and jruby
* create a #to_h and have it use symbols for keys
* add #to_json and #to_proto helpers on the Google::Protobuf message classes

ruby arrays don't throw an exception; they return nil.  Lets do the
same!

this fix also includes the ability to use negative array indicies

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

Includes repro test case from @wfarr.

Previously, we supported map fields in the Ruby DSL. However, we never
connected the final link in the chain and generated `map` DSL commands
for map fields in `.proto` files. My apologies -- I had been testing
with the DSL directly so I missed this.

Also fixed a handlerdata-setup-infinite-loop when a map value field's
type is its containing message.

- 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.

This adds the Map container and support for parsing and serializing maps
in the protobuf wire format (as defined by the C++ implementation, with
MapEntry submessages in a repeated field). JSON map
serialization/parsing are not yet supported as these will require some
changes to upb as well.

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'.

This adds a Ruby extension in ruby/ that is based on the 'upb' library
(now included as a submodule), and adds support for Ruby code generation
to the protoc compiler.