text: Title: Run librephotos from URL subdirectory
  Body: If librephotos is installed along other apps on same server or running behind reverse proxy it will be good to be able to run it from a subdirectory. Now it is running always from / and will be good to have option to run from /librephotos, for example.
  
  I tried to use librephotos docker images behind apache ssl terminating reverse proxy as https://example.com/librephotos, but api calls and almost any other urls are broken even if I use ProxyHTMLURLMap in apache.
  