e2e: move Sauce credentials out of source code (part 2)
e2e: move Sauce credentials out of source code (part 2)

.gitignore credentials.js so that modifications to the file are not
pushed/pulled into version control.

marklogic/marklogic-samplestack,laurelnaiad/marklogic-samplestack,supriyantomaftuh/marklogic-samplestack,supriyantomaftuh/marklogic-samplestack,ryanjdew/discovery-app-w-samplestack,marklogic/marklogic-samplestack,supriyantomaftuh/marklogic-samplestack,dmcassel/marklogic-samplestack,laurelnaiad/marklogic-samplestack,dmcassel/marklogic-samplestack,laurelnaiad/marklogic-samplestack,omkarudipi/marklogic-samplestack,ryanjdew/discovery-app-w-samplestack,supriyantomaftuh/marklogic-samplestack,marklogic/marklogic-samplestack,omkarudipi/marklogic-samplestack,ryanjdew/discovery-app-w-samplestack,omkarudipi/marklogic-samplestack,omkarudipi/marklogic-samplestack,laurelnaiad/marklogic-samplestack,dmcassel/marklogic-samplestack,dmcassel/marklogic-samplestack,ryanjdew/discovery-app-w-samplestack,marklogic/marklogic-samplestack