fix(deepExtend): Ensure dest is obj when src is obj

[TheSharpieOne]

currently deepExtend is not ensuring the destination is an object when the source is an object.
deepExtend currently does a similar check/set for the case of source being an array.
This PR adds the check for destination being an object and if not sets it to {}.

[brandonrobertz]

We need a unit test on this IMO

[TheSharpieOne]

Tests added for this case, but for a method such as deepExtend... it is seriously lacking tests to the point where adding just this one is almost pointless.

[brandonrobertz]

Is there a reason we're not using angular.merge?

[TheSharpieOne]

idk, I didn't make this thing, just trying to fix it. You can probably create a PR for replacing deepExtend with angular.merge... even go as far as making deepExtend just call angular.merge just so you don't have to replace references to it everywhere.

[brandonrobertz]

@TheSharpieOne Good idea about the PR. In the meantime I think your fix is good for now. I'm locked at 0.0.8 until I can trust this lib to not break me with a semver patch-version number update.

[pablojim]

Thanks @TheSharpieOne and @brandonrobertz.

[pablojim]

angular.merge did not exist when this package was written and only exists in angular 1.4 onwards...

Probably not worth breaking compatibility with lower versions for this one method.