Adding new version in constants.ts

Bump version

Merge pull request microsoftgraph#148 from microsoftgraph/version_bump

Bumped up the version for release

Bumping version number and re-run generating js files

Merge branch 'dev' of https://github.com/microsoftgraph/msgraph-sdk-j…

…avascript into dev

Bumping up version to 1.2.0

Bumping up version for release

Update README.md

Add Code of Conduct link