Adding Appium support for Saucelabs
Allow overriding the Sauce Labs sharing

- Update Sauce Labs privacy settings/marks
- Update README appropriately
Merge branch 'saucelabs_privacy'
Update version and changelog for v1.2

Update README as well
Output request headers when initial test for baseurl fails. Fixes #130

Version bump and update changelog for v.3
Only check the base URL from the main process when pytest-xdist is in use.