Implementing Helmet for Security
Removed strict transport security policy from security config; fixed issue with xframe options header only returning deny;
Removed CSP by default since node is only serving our API requests;
Updated readme with some info on security config.
Merge pull request #43 from clevertech/issue37

feat(helmet): Implementing Helmet for Security
Merge branch 'master' of https://github.com/clevertech/cleverstack-node-seed into issue20

Conflicts:
	config/index.js
	index.js
	package.json