Update CONTRIBUTING.md

'Done' label
Pre-release
Test Server
When issue is closed
Update CONTRIBUTING.md

All pull requests are made to 'development' branch.
Development branch is merged to 'master' after Test Server tests are finished.
Then Release is created and deployment to production is possible.
Quick fix for Issue #17 Remove pagination for VU
Merge remote-tracking branch 'upstream/master' into development
Merge remote-tracking branch 'upstream/development' into development
Small indentation fixes for code to look better
Empty space eleiminated
Merge pull request #49 from Bohdan-Tereta/development

Issue #17 Remove pagination for VU fixed