Fix album with songs deleting

See merge request !82

Deleting album with songs not allowed and causes alert

Fixes

See merge request !81

margins

See merge request !80

Milestone 4 update

See merge request !79

Merge branch 'milestone-4-zelnik' of https://gitlab.fi.muni.cz/xzelnik/music-band-manager into milestone-4-zelnik

Merge branch 'milestone-4-zelnik' of https://gitlab.fi.muni.cz/xzelnik/music-band-manager into milestone-4-zelnik

Add delete offer and delete activity

See merge request !78