Switch to mypy 0740 and some type additions

[LefterisJP]

No description provided.

[codecov-io]

Codecov Report

Merging #524 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #524      +/-   ##
==========================================
+ Coverage   77.03%   77.07%   +0.04%     
==========================================
  Files          50       50              
  Lines        4890     4890              
  Branches      717      717              
==========================================
+ Hits         3767     3769       +2     
+ Misses        938      932       -6     
- Partials      185      189       +4

Impacted Files	Coverage Δ
rotkehlchen/exchanges/exchange.py	93.69% <ø> (ø)	⬆️
rotkehlchen/accounting/accountant.py	86.42% <ø> (+4.52%)	⬆️
rotkehlchen/ethchain.py	55.76% <0%> (-2.57%)	⬇️
rotkehlchen/inquirer.py	90.06% <0%> (-2.49%)	⬇️
rotkehlchen/utils/misc.py	79.54% <0%> (-0.57%)	⬇️
rotkehlchen/server.py	59.88% <0%> (-0.29%)	⬇️
rotkehlchen/externalapis/cryptocompare.py	66.53% <0%> (+0.81%)	⬆️

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