Merge pull request #74 from Gayany/master

Adding null attributes support in schema builder
Merge pull request #40 from wso2-dev/master

Merge branch 'master' of https://github.com/wso2-dev/developer-studio
generate ui for null item array
refactor code
Merge pull request #75 from lsdeva/master

generate datamapper ui for null item array
Merge pull request #50 from wso2-dev/master

Merge pull request #37