Listen for change event for bound values

[DaveWM]

When you call localStorageService.bind, an event listener is now registered that is fired when the value of the local storage key changes, which updates the value and calls scope.$apply(). fixes #166

[coveralls]

Coverage increased (+0.43%) when pulling 9aed91157dad457b0d548ad6701d4e10836e60da on DaveWM:master into 3c5e2ec435f279869fbc18bab8ddb38f6429438d on grevory:master.

[YouriT]

Would appreciate to have that feature also :)

[coveralls]

Coverage increased (+0.58%) when pulling 98fd70b60d5316d23b001b80a2119dba4175ac15 on DaveWM:master into 3c5e2ec435f279869fbc18bab8ddb38f6429438d on grevory:master.

[a8m]

Further to your comment @DaveWM, thanks for the PR, I'll take a look later.

[tiagoroldao]

Are changes still required here? I wanted to start work on this, but saw the PR already existes for this functionality.

[bnbon]

+1 for this feature.

[windom]

+1 too :)

[STRML]

This won't actually work because storage events are only fired on other windows/tabs, not the window/tab originating the event. I've modified the PR to listen to internal events to do this instead, which seems to be working fine.

[eperret]

+1 as well