create to_json, serialize, deserialize methods on the Transaction object

[roks0n]

Proposed changes

Created to_json, serialize, deserialize methods on the Transaction object.

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (improve a current implementation without adding a new feature or fixing a bug)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Build (changes that affect the build system)
• Docs (documentation only changes)
• Test (adding missing tests or fixing existing tests)
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Checklist

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• 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

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[codecov-io]

Codecov Report

Merging #23 into develop will increase coverage by 0.27%.
The diff coverage is 58.46%.

@@             Coverage Diff             @@
##           develop      #23      +/-   ##
===========================================
+ Coverage    72.04%   72.32%   +0.27%     
===========================================
  Files           32       32              
  Lines          576      589      +13     
  Branches        53       54       +1     
===========================================
+ Hits           415      426      +11     
- Misses         134      136       +2     
  Partials        27       27

Impacted Files	Coverage Δ
crypto/serializer.py	74.57% <0%> (ø)	⬆️
...ypto/transactions/serializers/timelock_transfer.py	0% <0%> (ø)	⬆️
crypto/transactions/serializers/multi_payment.py	0% <0%> (ø)	⬆️
crypto/transactions/serializers/transfer.py	100% <100%> (ø)	⬆️
crypto/transactions/deserializers/transfer.py	100% <100%> (ø)	⬆️
crypto/transactions/builder/transfer.py	100% <100%> (ø)	⬆️
crypto/transactions/builder/base.py	95.65% <100%> (ø)	⬆️
crypto/deserializer.py	63.07% <41.17%> (ø)	⬆️
crypto/resources/transaction.py	83.18% <66.66%> (+0.18%)	⬆️

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