refactored out credentials into single credentials.yml file
Merge branch 'master' of https://github.com/avadev/AvaTax-Calc-SOAP-Ruby

Conflicts:
	AdjustTaxTest.rb
	CancelTaxTest.rb
	CommitTaxTest.rb
	GetTaxHistoryTest.rb
	GetTaxTest.rb
	PingTest.rb
	PostTaxTest.rb
	ValidateAddressTest.rb