Show status of new indexing in webpage

[MartinMikita]

The indexing process is now logging into the file, which could be used to get the status of indexing from the python and show the progress.

You can check the indexing process, which is logged into the file /var/log/sphinxsearch/sphinx-reindex.log inside the running container.

Tasks to be done to improve this:

• create a lock file, that index is in progress
• show parsed progress from the log (or entire file probably?) on the main page (if the indexing is in the progress)
• return an empty response when there is no index data (database is not running) and the index is in the process for each query
• delete this lock file in the end, and allow requests to be done

This should solve issues using this docker container with larger data for the first time by new customers, like #53