Pytest-dash

Fixed
- Fixed server closed assertion on non-english locales. [70](https://github.com/T4rk1n/pytest-dash/pull/70)

Fixed
- Fixed python 2 super call on subclasses of BaseDashRunner [68](https://github.com/T4rk1n/pytest-dash/pull/66)

Added
- Add `pytest_setup_selenium` hook [65](https://github.com/T4rk1n/pytest-dash/pull/65)

Added
- Behavior tests from yaml description. [54](https://github.com/T4rk1n/pytest-dash/pull/54)
- Plugin configuration hooks for selenium options (Currently only `webdriver`)
- Configuration from commandline
- Configuration from pytest.ini file.
- Added xpath wait_for wrappers.
- Added wait_for wrappers for multi elements find.
- Customizable behavior parsing thru `pytest_add_behavior` hook.

Changed
- Application runners (dash_threaded, dash_subprocess) refactored to a context manager with own selenium driver.
- Driver argument changed to `--webdriver`

Fixed
- dash_threaded now wait til the server has stopped in teardown.
- server runners now properly closes if there's an error in initialization. Fixes [57](https://github.com/T4rk1n/pytest-dash/issues/57)

Breaking Changes
Removed
- Removed `pytest-selenium` dependency, now incompatible, get the driver from the fixtures (eg: `dash_threaded.driver`).
- Removed `percy_snapshot` fixture.

Moved
- `utils.import_app` moved to `application_runners.py`

Added
- Base exception type: `PytestDashError` [23](https://github.com/T4rk1n/pytest-dash/pull/23)
- `DashAppLoadingError` [23](https://github.com/T4rk1n/pytest-dash/pull/23)
- Display the body html
- Display console logs
- Catch common errors early. [33](https://github.com/T4rk1n/pytest-dash/pull/33)
- Loop wait_for `_dash-app-content` and retry the url. [33](https://github.com/T4rk1n/pytest-dash/pull/33)
- Added `start_wait_time` and `start_timeout` to `dash_threaded` [33](https://github.com/T4rk1n/pytest-dash/pull/33)
- Add port option to `dash_threaded` and `dash_subprocess`. [28](https://github.com/T4rk1n/pytest-dash/pull/28)
- Add `start_wait_time` option to `dash_threadred` for waiting after starting the thread, default to 1 sec. [28](https://github.com/T4rk1n/pytest-dash/pull/28)
- Add more `wait_for` wrappers [41](https://github.com/T4rk1n/pytest-dash/pull/41)
- `wait_for_style_to_equal`
- `wait_for_property_to_equal`
- `wait_for_element_by_*`

Fixed
- `dash_subprocess` uses `_wait_for_client_app_started` instead of polling the output, fix subprocess tests on circle 13, [43](https://github.com/T4rk1n/pytest-dash/pull/43)

Fixed
- Fixed `utils.import_app` imported methods not having access to imports. [12](https://github.com/T4rk1n/pytest-dash/pull/11)

Changed
- Syntax for `utils.import_app` changed to dot notation, same as `dash_subprocess`.