add sum functionality estimate
Merge pull request #234 from vaibhavcisin274/vaibhav

add sum functionality estimate
working calendar part
remove conflicts 18-jul
Merge pull request #235 from vaibhavcisin274/anshul

Anshul
changes for product/service table and show
Merge branch 'master' of github.com:vaibhavcisin274/invoice-project into vaibhav
Merge pull request #236 from vaibhavcisin274/vaibhav

Vaibhav
changes 19 july