Merge pull request #2 from bolek117/mwitas

Mwitas
Merge pull request #3 from bolek117/mwitas

Mwitas
In CategoriesList class method name changed from GetCategoryById to GetCategory; in File classes null implementation of related interfaces
Merge branch 'master' into kzielinski
Merge branch 'kzielinski'
Bin folder deleted
Conflicts resolved