AngularJS-version of add prefix page

Created an AngularJS-version of the add prefix page. Links to it has been added to the prefix list (to allocate a prefix from a prefix) and the pool list (to allocate a prefix from a pool). Manual assignment is also supported, but there is no link to it so far.

It's still missing some of the flashy features such as scrolling to next relevant part of the page and animated background colors for highlighting.
Hm.. Now I'm back on track on this issue :)

The ```_provided``` variables are basically used to to control whether the widgets used to select allocation method, pool or prefix should be displayed or not, with the idea that they should be hidden if the information was provided in the URL and displayed if not. To be able to differentiate if the information was given in the URL or not even after for example the pool has been chosen (essentially, to know if the "selector widget" should be visible or not even after the value has been assigned), it seems best to have two variables for it.