Fix potential fatal error when the index is not set
Adding a missing semicolon
Coding standards
Readme updates
Bumping to 0.5.3
More readme updates
Updating readme.md
Fix undefined index notice
Merge remote-tracking branch 'upstream/master'

https://github.com/rinatkhaziev/wp-frontend-uploader/commit/b214d69c58223751ee380314feb8497b646fe307