Cleanup save_* family of methods

* Better YARD documentation
* Make `path` argument of `save_screenshpt` `nil` by default
* Add `options` argument for `save_and_open_screenshot`
Some doc fixes
Test should be tagged as :windows also
Update History.md

Fix typo
Use Rack::Lock to prevent concurrency when eager_load is false
Merge pull request #1398 from takashi/patch-1

Update History.md
Merge pull request #1390 from abotalov/doc_fixes

Some doc fixes
Merge pull request #1295 from abotalov/save_screenshot

Cleanup save_* family of methods
Merge pull request #1400 from jnicklas/rails_threading

Use Rack::Lock to prevent concurrency when eager_load is false
Merge pull request #1393 from route/master

Tests should be tagged as :windows also