Add index to deleted_at column in README

Rails normally returns the model on successful destroy and false if any
callback fails.

Fixes #104

Fixes #95

destroy! now once again calls destroy

This is because destroy! is called by :dependent => :destroy association definitions (yes, destroy! and not destroy), which means that associated records of a paranoid object would suddenly go missing... making it very hard to restore them!

So instead, it's now called really_destroy! and destroy! is just an alias for destroy once again

[ci skip]

Fixes #97

As per #92

Fixes #91

Fixes #81
Fixes #84

Conflicts:
	lib/paranoia.rb

Update/save callbacks should not be called at all during a destroy call, as would happen with the code from that PR.

Replaced deprecated gemcutter source

References: https://github.com/goncalossilva/acts_as_paranoid

Fixes #76

Use quoted table name in default scope (call me paranoid)

Applies changes suggested in #59 which did not apply correctly

Fixes #57

Update rails4 branch name in README

Fixes #72

Add Model#restore(id)