[FEATURE] Fix PEP 8 style and add comments

[FEATURE] Fix PEP 8 style and add comments
[FEATURE] Fix style code by PEP 8

[FEATURE] Fix style code by PEP 8 but some line longer 79

[FEATURE] comments and style PEP 8 in market.py

[FEATURE] No comment every single pylint warning
[FEATURE] Add comments to market.py

[FEATURE] Add comments to market.py

[FEATURE] Add comments to market.py
[FEATURE] Add comments with doc strings to market.py
Merge pull request #615 from Ignat99/feature

[FEATURE] Fix style code by PEP 8 for market.py
Revert "[FEATURE] Fix style code by PEP 8 for market.py"
Merge pull request #623 from OpenBazaar/revert-615-feature

Revert "[FEATURE] Fix style code by PEP 8 for market.py"
Upgrade to pyelliptic 1.5.4.
Merge pull request #627 from Renelvon/upgrade_pyelliptic

Upgrade to pyelliptic 1.5.4.
Add contributing guidelines
Various typo fixes suggested by @renelvon
Style, markdown, paragraph and other minor fixes.
Sections about code and PR documentation.
Restructure fixing-an-issue section.
Make section headers bold to stand out.
All kinds of style fixing.