Remove pre-installed softwares from prebuild steps 

Merge fixes from 3.4.x into master

Disable death tests on windows

Also remove cord related code

Use message name as defined in php runtime.

Merge pull request #3535 from drivehappy/clang_warn_cleanup

Merge pull request #3494 from drivehappy/clang_warning_macro

Add Elixir protobuf and gRPC to 3rd party doc

Fixing -Wexpansion-to-defined Clang warning

Fixing unused parameter warnings under Clang.

Fixing unused parameter warnings under Clang.

Remove C++11 features in io_win32.cc

- Use scoped_array instead of unique_ptr.
- Do not use string::front() and string::back()

Merge 3.4.x into master

* remove the parens from the cmp() lambda definition

https://github.com/PythonCharmers/python-future/pull/298

* remove the parens from the cmp() lambda definition

https://github.com/PythonCharmers/python-future/pull/298

Bump gemspec again

Prefer system distributed binaries/libraries.

protoc-artifacts: Bump JDK to 8u131

This reverts commit 703f414c.

* Drop Python 3.3 from testing & add Python 3.5, 3.6

Python 3.3 goes [EOL](https://docs.python.org/devguide/index.html#branchstatus) next month.

* Sync test.sh with the Python versions in tox.ini

* Define cmp() for Python 3

http://python-future.org/compatible_idioms.html?highlight=cmp#cmp

* Define cmp() for Python 3

http://python-future.org/compatible_idioms.html?highlight=cmp#cmp

Python 3 compatibility fixes: print(), long(), etc.

The future import is required to support the print(x, end=" ") parameter in Python 2.

http://python-future.org/compatible_idioms.html#file

Old style exception --> new style exception

Bump gem version for the next upload

Update testpypi URLs