New connection: created a password checkbox

Now we can switch the "Remember passwords" option directly on new connection form, where it is relevant and where most of users would probably look for it. Lot of other software with login form have the same option directly on the form as well, so most of users, including me, expect it to be there and might get confused or even think there is no such a feature when they don't see it there :)
Merge branch 'master' into qt5x