Remove hardcoded strings from DetailView

There were some strings in DetailView which were hardcoded or displayed directly from the data returned by the API and therefore could not be translated:
* dialog buttons (status, progress, rating)
* status text
* media type
* media status

I added functions to get the media type, media status and user status as integers to Anime/Manga class and added string-arrays to strings.xml. The integers returned by these functions are the array indices of the string-arrays so they can be used directly for string mapping (see ```getStringFromResourceArray()``` and following functions in DetailView).

Also replaced hardcoded strings in the dialogs by resource strings.