Verbose image loading error logs

ImageManager simply eats all helpful error messages so you have no clue why your image hadn't load.

Real life example which gives you nothing:
```
enroscar.ImagesManager﹕ Process url content://com.example/brandpack/restaurant_logo/snoac_st
enroscar.ImagesManager﹕ Not in mem content://com.example/brandpack/restaurant_logo/snoac_st
enroscar.ImagesManager﹕ Set loading for content://com.example/brandpack/restaurant_logo/snoac_st!160x160
enroscar.ImagesManager﹕ Key content://com.example/brandpack/restaurant_logo/snoac_st!160x160
enroscar.ImagesManager﹕ Current loaders count: 1
```