Fix vote, 2nd signature reg. and delegate registration + minor refactor

[roks0n]

Proposed changes

This PR fixes following transactions:

• Vote: proof
• 2nd Signature Registration: proof
• Delegate registration: proof

Along with above fixes I've also removed some unsued methods and removes name Transaction from the Builder's class names. It also fixes incorect naming of a transaction.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Refactoring (improve a current implementation without adding a new feature or fixing a bug)

Checklist

• I have read the CONTRIBUTING documentation
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

None

[codecov-io]

Codecov Report

Merging #44 into develop will increase coverage by 1.95%.
The diff coverage is 81.81%.

@@             Coverage Diff             @@
##           develop      #44      +/-   ##
===========================================
+ Coverage    77.52%   79.48%   +1.95%     
===========================================
  Files           39       39              
  Lines          712      697      -15     
  Branches        70       70              
===========================================
+ Hits           552      554       +2     
+ Misses         129      112      -17     
  Partials        31       31

Impacted Files	Coverage Δ
crypto/transactions/builder/timelock_transfer.py	0% <0%> (ø)	⬆️
...rypto/transactions/builder/delegate_resignation.py	0% <0%> (ø)	⬆️
crypto/transactions/builder/ipfs.py	0% <0%> (ø)	⬆️
crypto/transactions/builder/multi_payment.py	0% <0%> (ø)	⬆️
crypto/transactions/builder/base.py	92.3% <100%> (-0.55%)	⬇️
crypto/transactions/builder/transfer.py	81.81% <100%> (ø)	⬆️
crypto/transactions/builder/vote.py	84.61% <100%> (+17.94%)	⬆️
...ypto/transactions/builder/delegate_registration.py	85.71% <100%> (+7.93%)	⬆️
crypto/transactions/transaction.py	85% <100%> (ø)	⬆️
...ansactions/builder/multi_signature_registration.py	100% <100%> (+26.66%)	⬆️
... and 1 more

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