Needed to pick up a Java dependency change and re-populate the offline
repo.

[skip ci]

1. Added ruby22 and jruby tests to jenkins.
2. Added javascript tests to jenkins.
3. Added golang tests to jenkins.
4. Removed ruby19/ruby20 tests from travis. Support for ruby 2.0 has
   ended since 2016/02/24.
   https://www.ruby-lang.org/en/news/2016/02/24/support-plan-of-ruby-2-0-0-and-2-1/

Change-Id: Ie984b06772335352a4be7067ab2485f923875685

This also updates the version number to 3.0.0-beta4

Move to dotnet cli for building, and .NET Core (netstandard1.0) as target platform

This also updates the version number to 3.0.0-beta4

Version number for beta languages is updated to v3.0.0-beta-2.
Version number for alpha languages is updated to v3.0.0-alpha-5.

Protoc, C++ runtime and Java runtime are updated to v3.0.0-beta-1, other
languages are updated to v3.0.0-alpha-4.

Change-Id: Ifb4958e4f371b36f249faa466473f851697edb5c

Change-Id: Iae16dcae833959681a5c8e98764e5d1071e6fdcf

- Remove PY25 cruft.

- Selectively apply cleanups from 'python-modernize':

  - New exception syntax.
  - Use 'six' to handle module renames.
  - Use 'six' to handle text / binary stuff.

This PR covers most of the work from #66 which falls inside `python`
(rather than the Python code generation stuff in 'src').

Added __version__ attr to package so that scripts that check local
packages to see if newer versions are available can work.

Almost all Python packages have a version attr, and the vast majority of
them name it "__version__"

This reverts commit 5337cf56.

Added __version__ attr to package so that scripts that check local
packages to see if newer versions are available can work.

Almost all Python packages have a version attr, and the vast majority of
them name it "__version__"

committer: Jon Skeet <skeet@pobox.com>