RC3

New:
* Add "Delete all nmap scans" Button to maintenance tab
* Add "Delete all Webservices" Button to maintenance tab
* Button to reset the search on the journal page
* CSV download for nmap scan per device
* Insert Nmap scan results to db (only scans with results are saved in the db) (#271)

Fixed:
* Minor fixes and tweaks
* pialert-cli help: When the end of the command list is reached, the command prompt appears again automatically
* Fixed redirections in the event of an error (reported via mail)

Updated:
* pialert-cli: to update the database for the new function
* Readme: add Sponsor
* Readme: LINUX-DISTRIBUTIONS.md (reported via mail)
* Cleanup task extended (Nmap scan results)
* Remove/streamline old code
* Language files

Changed:
* Set timeout (60s )for all Nmap scan types
* The counter of the currently active scans in the status box (settings page) has been replaced by a simple display (Scans running / No Scans running). Depending on the Linux distribution, the counter varied by +/- 1. The original reason for the introduction of the counter was a ramping up of arp-scan processes, which has not been a problem for many Pi.Alert versions.
* Update Check: Check for a special installation directory to avoid issues like #283 or #281
* Nmap scan infos moved to faq/help page

Removed:
* Remove Nmap session log button from settings page