Validate scrapped data

[Resmung0]

It's necessary to validate all scrapped data from each web site. I've analyse each column from dataframe searching for null values and inconsistencies (values that don't make sense).

1. Nuuvem:
   1.1 DEVELOPER:
   - [ ] Inconsistencies;
   - [ ] Null values;
   1.2 DRM:
   - [x] Inconsistencies;
   - [ ] Null values;
   1.3 GAME_MODE:
   - [x] Inconsistencies;
   - [ ] Null values;
   1.4 GENRE:
   - [x] Inconsistencies;
   - [ ] Null values;
   1.5 OS:
   - [x] Inconsistencies;
   - [x] Null values;
   1.6 PRICE:
   - [x] Inconsistencies;
   - [x] Null values;
   1.7 PUBLISHER:
   - [ ] Inconsistencies;
   - [ ] Null values;
   1.8 RATE:
   - [ ] Inconsistencies;
   - [ ] Null values;
   1.9 RELEASE_DATE:
   - [x] Inconsistencies;
   - [x] Null values;
   1.10 TITLE:
   - [ ] Inconsistencies;
   - [x] Null values;