OC-4235: 'delay-loading' changes to reduce load-time

Here are findings,

# knife-core(no-plugins)
	# before changes
		real 	0m0.744s
		user	0m0.688s
		sys  	0m0.052s

# knife(with knife-google, knife-hp, knife-ec2, knife-windows,knife-terremark)
	# before changes, 
		real 	0m2.421s
		user	0m2.272s
		sys  	0m0.140s

	# After changes, 
		real 	0m1.403s
		user	0m1.312s
		sys  	0m0.072s


Environment:
1. Chef Version: 10.14.2
2. Ruby Version: 1.9.3p194
3. Gem Version: 1.8.24