Fixes:
  https://github.com/google/protobuf/issues/502
  https://github.com/google/protobuf/issues/425

upb no longer requires -std=c99 but the Ruby/C
code still uses C99 features.

Since this version of upb supports C89, all of the
extra compiler flags are no longer required.

Also fixed lines with > 80 char length.

- Alter encode/decode paths to use the `upb_env` (environment)
  abstraction.
- Update upb amalgamation to upstream `93791bfe`.
- Fix a compilation warning (void*->char* cast).
- Modify build flags so that upb doesn't produce warnings -- the Travis
  build logs were pretty cluttered previously.

- 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

* update docs to simplify build steps
* Gemfile.lock seemed to have an older version specified
* do not check in the pkg dir

Includes repro test case from @wfarr.

Change-Id: Idb29077c153530de78ce28c094442aa8f51ddd25

Change-Id: I33479e529b060e4fed532a827a386d3baecc835e

Change-Id: I54df314660cdb861ad8c4da75a08d4cb97faf638

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

Change-Id: I8c3717f549c9b4e9d07c77ec5875c9cd62b296ac

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.