Add a swift_prefix file option.

Swift generators should default to CamelCasing the proto package and prefixing
symbols with that, but this option allows developers to override that behavior
with something custom if they desire.

Fixes https://github.com/google/protobuf/issues/1833

Integrated internal changes from Google

This makes a couple of changes to fix the tests for JRuby 1.7:
- Avoid using assert_false since that assertion seems not to exist in
  older versions
- Disable a test related to respond_to? for JRuby. It's hard to tell
  what is going wrong here but it looks like probably a JRuby bug that
  has been fixed in more recent versions.

In Python 3 the values() method on a dictionary returns a view instead
of a list, so we need to explicitly convert that to a list.

This seems to be necessary to prevent warnings in some compiler
configurations, particularly for tag numbers that are too large to fit
in a signed 32-bit int.

The curly brace syntax for sets was introduced in Python 2.7, and so for
compatibility with 2.6 we need to avoid using it for now.

Support grpc plugin in py_proto_library

A new test is now passing and so we can remove it from the failure
whitelist.

Fixed JSPB test failures

C++: Fix use with GOOGLE_PROTOBUF_NO_STATIC_INITIALIZER

Restore jenkins files.

Behavior of define GOOGLE_PROTOBUF_NO_STATIC_INITIALIZER has been
altered between 337a028b and cc8ca5b6 for C++.

See github issue #2385 for further details.

The last up-integration from github to google3 was made at commit
e28286fa but somehow the change in
that commit is not actually in the up-integration CL and as a result
that change was reverted by the down-integration. Restoring them
should make the jenkins tests running again.

Update README.md

Add LL to large constant

needed a grave here, not an apostrophy

Some compiler will report: 'error: integer constant is too large for long type'

In php, class name cannot be "Empty". Modified code generator to (#2375) generate GPBEmpty instead (for google.protobuf.Empty only). Also change
runtime code to work with the new generated code accordingly.

Class is final but declares protected field

typo in readme

Add missing include in message_lite.cc

More Ruby-eqsue interface

JS: Fix for high utf-8 codepoints.

Fix #include in js_generator.cc