Make retry for list download configurable (#308)

[kwitsch]

New configuration options:

• blocking.downloadAttempts
• blocking.downloadCooldown

[codecov]

Codecov Report

Merging #338 (0f33753) into development (e882fa0) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##           development     #338   +/-   ##
============================================
  Coverage        96.11%   96.12%           
============================================
  Files               30       30           
  Lines             2216     2221    +5     
============================================
+ Hits              2130     2135    +5     
  Misses              56       56           
  Partials            30       30           

Impacted Files	Coverage Δ
config/config.go	91.48% <ø> (ø)
lists/list_cache.go	94.38% <100.00%> (+0.06%)	⬆️
resolver/blocking_resolver.go	100.00% <100.00%> (ø)

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[0xERR0R]

This is cool! Thx and 🤝

[0xERR0R]

closes #308