Post csharp landing fixup.

Re-add the objc prefix that got removed by accident.
Regenerate the generated descriptors (C++ and ObjC).

[PYTHON] Only generate protos in development

Fixes #333.

ruby: Encode decode cleanup and behavior normalization

Make generate_protos.sh Windows-friendly.

Refactor Travis tests: split configs and run in parallel.

Merge protobuf C# into master (only C# proto2 is supported)

ruby: make repeated_field quack like an array

To my surprise, executing generate_protos.sh used the version of Bash installed with Git for Windows by default.
After a few modifications to detect the most appropriate protoc to use, this worked pretty simply.
This change also:
- adds generation of the address book tutorial proto,
- fixes the addressbook.proto to specify proto2 explicitly (to avoid a warning from protoc; I don't think we want warnings...)
- fixes the addressbook.proto C# namespace (which I thought I'd done before, but apparently hadn't)
- includes the regenerated UnittestCustomOptions.cs apart from the DescriptorProtoFIle => Descriptor change

Add Ruby to Travis testing

Integrate changes from latest master branch into csharp branch.

- 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.

Update README.md for C#

Remove the C#-specific field_presence_test.proto, using unittest_no_field_presence.proto instead.

* 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

This is the start of establishing a C# namespace of "Google.ProtocolBuffers.TestProtos.Proto3" for proto3-syntax protos.
We could optionally split the directory structure as well into Proto2 and Proto3 for clarity.

C# generate_proto.sh and buildall.sh scripts

C# cleanup