making decoupling of browser extension from base implementation
ARQGRA-455 Pass original arguments to onload/onreadystatechange
Updated README for screenshooter extension

- added link for upstream API documentation
Merge pull request #120 from smiklosovic/ARQ-1838

making decoupling of browser extension from base implementation
fix wrong merge of 'master' to '2.1.x' (d20ab76b3bbda0484aa7871b9de20910e32db097)