Extract the twisted greenlet initialization to a separate function

[vtitor]

Add an ability to use the plugin functionality in pytest hooks.

Example of usage:

import pytest

pytest_plugins = "pytest_twisted"

def pytest_configure(config):
    pytest.init_twisted_greenlet()
    ...

The similar stuff was requested in this issue #8. Additionally, I added config for running tests at travis-ci.

@schmir, @christianmlong Could you help me with this pr, please?

[schmir]

Hi vtitor, thanks for the PR.

I'm sorry, I don't maintain pytest-twisted anymore and it looks like @christianmlong is also inactive.

Do you want to take over maintainership? (I don't have the appropriate privileges to make you a maintainer, but I guess we can get someone from pytest-dev to do that).

[vtitor]

Hi @schmir, thanks for the response. I will be glad to become the maintainer of this repository.
@pytest-dev Could you help with this, please?

[vtitor]

@christianmlong, @hackebrot, @nicoddemus I'm sorry to bother you, but I need your help. Could you please grant me access?

[nicoddemus]

Hi @vtitor, thanks for taking interest in taking over the maintenance of this plugin, I'm just hearing about this thread now (I think in order to ping pytest-dev you need to ping @pytest-dev/core, not @pytest-dev).

I've sent @christianmlong an email asking him if he is not maintaining the plugin anymore and if we can add @vtitor as new admin of this repository. We will have to wait at least a month to move this forward though, as stated by our policy:

Repository owners can rest assured that no pytest-dev administrator will ever make releases of your repository or take ownership in any way, except in rare cases where someone becomes unresponsive after months of contact attempts. As stated, the objective is to share maintenance and avoid "plugin-abandon".

In fact, I think we should open a separate issue to track this so it doesn't get mixed with this PR, so I opened #11. We can move discussion about this over there.