Allow bypassing checksum with a flag

[John-Gee]

• What do you want to happen?
  It'd be nice to be able bypass the check, or simply hide the banner that pops up about it with a toggle.
• If not clear, why do you want it?
  We're currently distributing nzbhydra2 through AUR on Arch with some patches to the py3 wrapper.
• Do you think it's something only you need or something that might be popular?
  I think having more toggles could be useful for others.
• If not clear, explain the use case.
  Not sure if it's the best way, but right now we have to ship the OG wrapper and a renamed copy aside to not have these warnings.
  There could be other toggles we would ask for, but let's start simpler.

Thanks!

[theotherp]

Can be disabled by setting the environment variable NZBHYDRA_DISABLE_WRAPPER_CHECK in 5.1.2

[John-Gee]

Awesome, I look forward to 5.1.2.

Thank you!