Merge pull request #3 from tristanlins/master

Multiple improvements
database.sql remove for contao 3.1
find ImageId by Cache
remove end of file
view avatar in member- and userdata
add author namespace
Bugfix: no image size
Add support for renaming avatars and make doNotOverwrite=true by default.
Reformat and cleanup code.
While renaming avatars, prevent overwriting existing files.
Enable contao class overwrite feature by removing developers namespace in usage.
Make default fallback image configurable.