chore(js/handler.base.js): improve readability
feat(js/*): #934 - allow pause for chunked uploads

- Feature is completely functional for S3 and traditional endpoints
- Chunked uploads only
- UI component & API methods for pause & continue
- Status text update (UI) after pause
- New qq.status value (PAUSED)
- Refactor of click event handler module for file buttons
- TODO: Unit tests & docs
test(*): #934 - some unit tests for pause feature
fix(js/templating.js): #934 - fix IE8 and older
docs(docs/*): #934 - document pause feature

[skip ci]
feat(js/*): closes #934 - feature flag, a few small fixes
docs(docs/features/pause.jmd): #934 - clarification in feature doc

[skip ci]
chore(test/raytest-jquery.html): add pause/continue to dev test page

[skip ci]
docs(docs/features/pause.jmd) #934 - continue behavior clarification

[skip ci]
Merge branch 'feature/pause' into develop
chore(*): #934 - Increment build after pause feature merge