SignNow rebrand in LICENSE + README, expand .gitignore

[PetrVakulenko]

By creating this pull request, I confirm the following:

• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I updated the CHANGELOG.

Types of changes:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Link to issue (if exists):

Small description of changes:

Thanks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.50%. Comparing base (4afb90e) to head (dce00c4).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #182   +/-   ##
========================================
  Coverage    83.50%   83.50%           
========================================
  Files           91       91           
  Lines         1394     1394           
  Branches       174      174           
========================================
  Hits          1164     1164           
  Misses         187      187           
  Partials        43       43           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.