configuration should be per instance

[slillo]

Something similar was requested on #176, but issues has been closed.

I would like to use angular-filemanager multiple times with different configuration in the same page. Could be very useful to pass custom configuration to directive scope using syntax like:

Where vm.cfg1 could be something like {listUrl: "", ...}.

This behaviour could be very useful, in order to use angular-filemanager as a new type of angular formly field.