Do not navigate to the unlock page if there's nothing to unlock

[reyraa]

Expected behavior

If the account has unvoted delegates and has some LSK to be unlocked, they should be able to navigate to the unlock LSK page. but if they have just voted and there're no LSK waiting for unlock, they should not be able to navigate to that page.

Actual behavior

The unlock balance link in the wallet page navigates to the unlocking model which crashes.

Which version(s) does this affect? (Environment, OS, etc...)

2.0.0-alpha.7