[46594597] replace mongodb with postgresql

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge branch 'master' of github.com:vmw-tmpst/heroapp-TeenyURL into postgres

Conflicts:
	README.md
	app/lib/ServiceBinding.js
	test/ServiceBinding-unit-test.js

Signed-off-by: Henry Chen <hchen@vmware.com>
[46594597] replace mongodb with postgresql[2]

code refine based on comments

Signed-off-by: Henry Chen <hchen@vmware.com>
[46594597] replace mongodb with postgresql[3]

more code refine.

Signed-off-by: Henry Chen <hchen@vmware.com>
[46594597] replace mongodb with postgresql[4]

more code refine to make code look better

Signed-off-by: Henry Chen <hchen@vmware.com>
rename PostgreSql to PostgreSQL

Signed-off-by: Henry Chen <hchen@vmware.com>
correct a typo within error message.
Signed-off-by: Henry Chen <hchen@vmware.com>
Merge pull request #7 from Henry-CF/postgres

[46594597] replace mongodb with postgresql