Test wouldn't fail even if they should

Test wouldn't fail if there is actually nothing happening in the save
and query.

The object would still hold its original value and therefore the test
would pass without doing anything at all (eg. fetching new data from the
keychain).
Merge pull request #45 from hashier/fix_nil_test

Test wouldn't fail even if they should
Move to XCTest
Add shared scheme
Fixed __bridge_transfer on an extern constant
Merge pull request #49 from sanekgusev/bridge_transfer_fix

Fixed __bridge_transfer on an extern constant
Merge branch 'master' of https://github.com/soffes/sskeychain