0.10 - Execution of actionstart on demand (fixes gh-1741)

[sebres]

• implemented execution of actionstart on demand, if action depends on family (conditional);
• new action parameter actionstart_on_demand (bool) can be set to prevent/allow starting action on demand (default retrieved automatically, if some conditional parameter param?family=... presents in action properties), see action.d/pf.conf for example;
• additionally actionstop will be executed only for families previously executing actionstart (starting on demand only)

Closes #1741

[coveralls]

Coverage decreased (-0.005%) to 97.091% when pulling ca18270 on sebres:0.10-actionstart-on-demand into 05f5c6e on fail2ban:0.10.

[codecov-io]

Codecov Report

Merging #1742 into 0.10 will increase coverage by 0.05%.
The diff coverage is 98.5%.

@@            Coverage Diff             @@
##             0.10    #1742      +/-   ##
==========================================
+ Coverage   94.88%   94.93%   +0.05%     
==========================================
  Files          77       77              
  Lines       11912    11951      +39     
  Branches     1842     1858      +16     
==========================================
+ Hits        11303    11346      +43     
+ Misses        345      342       -3     
+ Partials      264      263       -1

Impacted Files	Coverage Δ
fail2ban/client/actionreader.py	87.23% <100%> (+2.45%)	⬆️
fail2ban/tests/servertestcase.py	92.85% <100%> (+0.08%)	⬆️
fail2ban/server/action.py	95.46% <97.87%> (+1.65%)	⬆️
fail2ban/server/utils.py	87.8% <0%> (-0.41%)	⬇️

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[coveralls]

Coverage increased (+0.03%) to 97.13% when pulling daa13eb on sebres:0.10-actionstart-on-demand into 05f5c6e on fail2ban:0.10.