Merge pull request #3 from antonkorotkov/development

Fix version
Delete .DS_Store
Merge pull request #4 from antonkorotkov/development

Ignore
Merge pull request #5 from antonkorotkov/development

API reference for help tab
Merge pull request #6 from antonkorotkov/development

API documentation fixes
Merge pull request #7 from antonkorotkov/development

methods drafts
Merge pull request #8 from antonkorotkov/development

New method pay invoice
Merge remote-tracking branch 'upstream/development' into development