Ensures that multiple tags are being honored, instead of just getting the first one

[Johan3F]

It relates to this issue: #1279

When merging tags, only the name was being used, but when the tags are loaded from the json sidecar file, only the value is expected, having only the name set to "".
Aside from that, the value is also used for manage the asset tags for the same reason.

A tiny cleanup of a for loop that was initializing a variable that was never used

[kuzyn]

Would that possibly also fix the issue where when using the --folder-as-tags=true switch, if an image appears in two folders, only the tag from the first encountered folder is associated to the image? See #1069

[Johan3F]

hi @kuzyn.
I've been running some tests and not, this wouldn't cover that.
For what I've seen, that bug needs some extra handling on the:

// run.go file l384
	case AlreadyProcessed: // SHA1 already processed
[...]
	case SameOnServer:
[...]
	case BetterOnServer: // and manage albums
[...]

I've tried to create a quick solution for that bug, but it's a bit more involved and it might require some decision making from the maintainers that I'm able to do on my own (Is it considered then discarded? it currently is, but if that's fixed, wouldn't it be?)