Fixes problem with searching links by text with non ascii characters.
Fixes problem with searching links by text with non ascii characters in zopebrowser.
Merge pull request #294 from kidosoft/fix-encoding-error

Fix encoding error
making Browser.cookies.all() behave the same in all drivers, consistent with Browser.cookies.add() and added docs about it (closes #295)
changed the optional browser.cookies.all parameter name to verbose and fixed the import of cookies from its return